© 2021 Bernard SUZANNE Last updated April 25, 2021
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Lexicon of Greek words important
for understanding Plato

(Revised and enriched version of February 28, 2021)

(Also available in pdf format as appendix 2 of  "Plato, the Esssentials" by clicking here)


Agathos, agathon
Daimôn, daimonios
Dialektikos, dialektikè
Epithumia, epithumètikon

Klinè, klinein

Krisis, krinein
Philos, philia
Phusis, phuein

Sophos, sophia
Sôphrosunè, sôphrôn
Thumos, thumoeides

Note : an indented word refers to an entry for anther word in which this word is also delt with and appears in blodface in the text.


I have included in this lexicon words particularly important in the dialogues, but I’m not trying to look for a “technical” meaning that these words might have for Plato, but on the contrary to explore the range of meanings of each word since Plato, even when he “specializes” a word in a specific context, never loses sight of the other possible meanings of the word (see for instance the case of ousia), precisely to be able to play with it on occasion. This is what makes the translation into English (or any other language) difficult since in most cases, no English word candidate for the translation of one or another meaning of a Greek word has the same range of meanings, which leads to losing some or all of the overtones Plato is playing with. This is why, in the above paper, I keep some Greek words, even at the cost of giving one of its possible translations between parentheses, or on the contrary to use an English word followed by the Geek word it purports to translate. The most obvious example of this difficulty is the case of the Greek word logos, for which each specialized translation into English based on context suppresses the many overtones the word had in Greek. In fact, one way of describing Plato’s dialogues is to see them as a lengthy reflection on logos as what distinguishes human beings from all other animals: what is logos, how does it work, what does it allow us to grasp beyond the words it is made up of and of what use might it be to help us live our lives of human beings? Thus Plato doesn’t want the least to fix a unique and precise meaning for each word, but tries on the contrary to play with the flexibility, vagueness and ambiguity of language to help us go beyond words to reach what they somehow attempt to point at. But this doesn’t mean he is not careful in choosing his words, far from it, whether to keep using a specific word in a given context or on the contrary to deliberately vary his vocabulary when he doesn’t want a given word to become “technical” by specialization. Two examples will make this clearer. In the allegory of the cave, Socrates says about the chained anthrôpoi that they are capable of dialegesthai (“dialogue”, Republic VII, 515b4) and that, as a result, they give names to the shadows they see moving in front of them; on the other hand, about the anthrôpoi hidden behind the wall and bearing statues and artefacts showing above the wall, he says that some of them talk, using the verb phtheggesthai (515a2, 515b8, 515b9). This verb may mean “to talk” when the subject is an human being, but it has a much broader sense, and can be used about animals and even about things in the general sense of “to make a noise”. This way, Plato makes a difference between the anthrôpoi as thinking beings capable of knowledge (the prisoners), who produce a logos having meaning and dialogue with one another, and the anthrôpoi as objects of knowledge (the bearers behind the wall in the cave), whose speeches are only, as physical phenomena in the sensible world depicted by the interior of the cave, noises among other. And what proves that this is not merely a stylistic device and a random choice to avoid monotony is that he reuses three times the verb phtheggesthai, always about the bearers, including twice in the same sentence within a few words. But when one of the prisoners is freed and a conversation ensues with one of those who freed him, he returns to the verb legein (root of logos, 515d2). Thus, Plato makes a clear distinction between speech as an audible physical phenomenon (“noises”) and speech as intelligible (a logos) and choses the appropriate verb depending on which viewpoint on speech he wants to stress in each case (this distinction is indeed not limited to the allegory of the cave and, in most cases, when Plato uses the verb phtheggesthai about human beings in the dialogues, it is to refer to speech as an acoustic phenomenon). On the contrary, when, in the Sophist, the stranger examines possible combinations of five notions he has taken as examples (being, same, different, rest, movement, Sophist, 253b9-258c6) and wants his reasoning to assume no prior “ontology” and be acceptable to “sons of the earth” as well as “friends of eidè” and having the broadest possible bearing, to name from a generic standpoint what may “partake” in certain “mixes” but not in others, he deliberately keeps changing vocabulary, using at times words appealing to the sons of the earth, phusis (“nature”, derived from the verb phuein meaning “to grow”) and genos (“family, kind”, derived from the verb gignesthai, meaning “to be born, to become”), at times words more likely to please “friends of eidè”, eidos itself and idea, at still other times a more neutral word which might satisfy both, ousia (“beingness”). And this doesn’t mean that to him, these words are synonymous, but that the principle he is presenting works no matter which one of these words is chosen and what the exact meaning assumed for it is. Whether one thinks of rest and movement as “natures (phusei)”, “kinds (gene)”, “appearances (eidè)”, “ideas (ideai)” or “beingnesses (ousiai)”, whether a materialist (“son of the earth”) or an idealist (“friend of eidè), and whatever the meaning assumed for “rest (stasis)” and “movement (kinesis)”, no one can accept that “rest is the same as movement” and everybody would accept that “rest is different from movement”,  which is enough to prove that words cannot be assembled any way one wants and that there is an “externality” imposing its law upon language for it to have meaning and say the “truth (alètheia)”.
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Agathos (adjective; neuter agathon): “good” in all the senses of the word, physical as well as moral; the neuter form used with the article as a substantive, to agathon, is used by Plato to designate “the good” as what gives value to everything, not limited to some sort of moral Good with a capital “G”, since for him, there is a “good” of the body as well as a “good” of the soul, and indeed of each part of the soul, desires as well as reason. In the plural, ta agatha refers to the multiplicity of “good things/attitudes/actions/thoughts/…”, that is, to all the instances of whatever may be said to be “good”. For Plato, to agathon is to the intelligence what the sun (and more generally, light) is to sight, to the extent that any human being always seeks what is good for him/her in all his actions, not as a means toward something else, but as an end, and that intelligence is given human beings to reach this goal.
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Alètheia (noun): “truth”. The word is a substantive derived from the adjective alèthès, whose etymological meaning is “not hidden”, “unveiled”. The path toward truth, pictured in the allegory of the cave, is thus a progressive “unveiling” (the shadows of the statues, then the statues, then the shadows and reflections of anthrôpoi, then the anthrôpoi themselves, seen in the light of the sun/“good”), each step leading to a richer and more comprehensive apprehension of human beings, without getting rid of what had been perceived in the previous steps, but putting it in a different perspective and adding new insight.  The tool for this unveiling in the human beings that we are is logos an thus, in this perspective, truth is a property of logos, the fact for it of “[saying] beings as it is” (legei[n] ta onta hôs estin; Sophist, 264b4), that is, to reflect through relations established by a logos between the words it uses the relations between the beings that these words pretend to refer to.
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Anèr (noun; gen. andros, pl. andres): “man” as opposed to “woman (gunè)”, that is, taking into account the sexual difference between male and female.
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Andreia (noun): this word, derived from anèr, means “courage” in a perspective where courage can only be displayed in warrior’s fight and thus can only be a masculine virtue. A translation reflecting this bias is “manhood”, or “virility”, which is the counterpart of andreia on Latin roots, since vir is the Latin equivalent of anèr.
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Anupotheton (adjective, neuter of anupothetos): this adjective is probably a neologism coined by Plato to qualify, in the analogy of the line at the end of book VI of the Republic, the “principle (archè, see this word)” toward which the process associated with the second segment of the intelligible, the one leading to true “knowledge”, must ascend. This word is formed by adding a privative alpha to an adjective derived from the aorist form of the verb hupotithenai, whose etymological meaning is “to put under”. Thus, anupotheton etymologically means “not put under” and not “unhypothetical”, a transcription rather than translation sometimes used to render it in English, but which has the defect of importing the usual meaning “hypothetical” has taken in English, that of “uncertain”. What Plato means when qualifying the principle he is talking about as anupotheton is that it is not stated to serve as a support to reach something else, as a “step” to reach higher, but that it is a principle beyond which there is nothing more to try to reach by “climbing” upon it. If we also notice that the word used by Plato to refer to what I have called a “principle”, archè (see this word) may refer both to what is ahead and toward which we move and what is at the origin, we may look at this archè as both a principle, but a principle which is not only at the origin but also sets a direction, that is, a leading principle, and the direction it points toward, the end (telos) it leads toward. This principle, though Plato does not explicitly say so, is obviously to agathon, which, as the ultimate end sought by all human beings, is indeed anupotheton in the sense I just described.
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Anthrôpos (noun; pl. anthrôpoi): “man” as a species, as opposed to “animal” or “god”, independent of sex, that is, “human being”. In Greek the word may be used indifferently with the masculine or feminine article, without change of ending.
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Archè (noun): substantive derived from the verb archein, whose primary meaning is “to lead/show the way”, and from there, “take the lead, begin” leading to the meaning “be a leader, rule, govern, command”. From these various senses of archein, the various senses of archè are derived, either “beginning, origin, principle”, or “command, sovereignty, power”. But the problem with this word is that there occurs in our understanding, or at least in the images it suggests, a reversal which ends up completely distorting this understanding. Starting from the idea, implied by the original meaning of the verb archein, of someone before us, walking ahead and showing the way, whom we follow, or of something before us which is a goal toward which we progress, we end up, through the idea of beginning taking the place of that of “first” in order, that is, ahead of us, then of principle and eventually of origin, to the image of something which is at the start and which we move away from and eventually which is behind us. When Plato, in the analogy of the line, mentions an archè anupotheton, we should understand archè in all its range of meanings: at the same time a first principle of action, a leading principle which orients our action and eventually the goal which guides us and toward which we move.
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Aretè (noun): this word is often translated as “virtue”, which gives it too exclusively moral a connotation which it doesn’t have in Greek, where it has quite broad a range of uses, not only about human beings, but also about animals, plants and eventually almost anything: the aretè of something is what makes this thing best in what it is intended for, what constitutes its “excellence”. Thus, there is a close relationship between aretè and agathon (“good”): aretè is what makes what the word applies to “good (agathon)” to the highest possible degree for what it is meant to do, for its end/purpose. Aretè is the central theme of the Meno, which opens on a question of Meno asking Socrates if, in his opinion, human aretè can be taught, or results from experience, or is a gift of nature or still something else.
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Autos (pronoun; fem. autè, neuter auto): this pronoun, which may have different meanings depending upon how it is used in a phrase, including “self/oneself” and  “by oneself/itself” when it is immediately preceded by  the article, and be used in certain contexts as a personal pronoun (“he, she, it”), is particularly important in Plato in two specific grammatical constructs.
In expressions taking the form autos ho *** or ho *** autos (masculine), autè hè *** or hè *** autè (feminine), auto to *** or to *** auto (neuter), translated as "the *** himself", "the *** herself" or "the *** itself", sometimes reinforced by kath' hauto meaning “in/by himself/herself/itself, as such”, it purports to insist on the fact that what we are talking about is *** (for instance “the good” or “the just” or “man” or “the bed”) in itself and not the appearance (eidos/idea) it takes for us through our senses and intelligence (nous) expressed by means of words and logoi, in short, the pragma (“thing”, see this word) which is at the origin of the pathèmata (“affections”) felt by our senses and intelligence in its presence. When, at Republic, VII, 516a5-8, Socrates opposes the « view » by the mind of the prisoner outside the cave of men and the other things through their (intelligible) “shadows” and “reflections” to the “sight”, again by the mind, of the auta, which constitutes the final goal of the progression outside the cave regarding what was present inside, this auta refers to “things” themselves no longer seen through visible (inside the cave) or intelligible (outside the cave) shadows and reflections, that is, through their visible appearance (the shadows inside the cave) or their description through words ( the shadows and reflections outside the cave). These auta are described by Socrates in the myth of the winged chariot of the Phaedrus (Phaedrus, 247b-248b) as “the colorless, formless, impalpable beingness really being” (hè achrômatos te kai aschèmatistos kai anaphès ousia ontôs ousa ; Phaedrus, 247c6-7) and are said to reside on the other side of the vault of heaven, in a place “above the heavens” (huperouranios) accessible only to gods and where only a few human souls having made efforts to follow one or another of these gods may hope to catch a glimpse of them from afar, without being able to move on the other side of the vault of heaven, which suggests that to apprehend them as they are is not within the power of the human soul.
Besides, the form tauton, contraction of the neuter substantive form to auto, used in the sense of  “the same”, is the form used by the Elean Stranger in the Sophist to designate one of the five “very large families” (megista genè), along with to on (“being”), thateron(contraction of to heteron,”the other/the different”), kinesis (“movement/change”) and stasis (“rest/changelessness”), of which he analyzes the mutual relations, and by Timaeus who makes it one of the components of the soul, along with to heteron/thateron (“the other”) and ousia (“beingness”) (Timaeus, 35a, sq.). Speaking in this way of “same” and “other” as components of the soul, Plato wants us to understand that the power that human beings have to develop a logos in order to dialogue (dialegesthai) with one another stems from the ability that the human mind has to discern “sameness” and “otherness”, that is, resemblance and difference, in perceptions of their senses and mind allowing them to give names to “families” (genè) distinct from one another identified on the basis of resemblances justifying the attribution of an eidos (see this word) common to all members of any one of those families  (see Republic VII, 515b4-5).
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Daimôn (nom): in Homer, “god” ; after Homer, this word ends up designating semi-divine beings inferior to the gods strictly speaking (theoi, plural of theos), but the translation as “demon” (one of the English word derived from it, along with “daimon” and “daemon”) is misleading after twenty centuries of Christianism because the word, in the time of Plato, had no negative bias whatsoever suggesting it applied exclusively to evil creatures (hence the English variants “daimon” and “daemon”, which don’t have such a bias). In the myth of Er which ends the Republic, Socrates presents the souls about to reincarnate choosing each a daimôn associated with a specific pattern of life and who will oversee them during their whole new life (Republic X, 617e). When talking about the divine sign which sometimes stops him from doing something, he uses the expression daimonion ti (“something divine”), using the adjective daimonios derived from daimôn (see for instance Apology, 31c8-d1).
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Dèmiourgos (noun): etymologically, “one doing some task (ergon) for the people (demos)”. In the usual sense, “craftsman”. It is the word Plato uses in the Timaeus to describe the creator of the Universe, the one introducing order (kosmos) in it to make it a Cosmos. This is what explains the meaning of the word “demiurge” derived from it.
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Dialegesthai (verb) (modified May 8, 2021): verb derived from the middle form legesthai of legein (“to talk”), also at the root of logos (see this word), with the adjunction of the prefix dia-, meaning “through, among, in the midst of, throughout, by, between”. Dialegesthai means “talk with one another, dialogue”. This verb, or rather the activity it describes plays a major role in Plato’s thought since it is the dialegesthai which makes logos possible and provides the means of putting its relevance to the test. But, above all, it refers to the activity most characteristic of man (anthrôpos), animal (zôion, that is, living being geared toward action, as implied by life) designed to live in communities (politikos, implied by dia-, meaning "one with another") and endowed with logos (logikos, implied by -legesthai), not that it suffice to talk with others to be a man worthy of that name, but because it is by best practicing this activity, thus in being most properly dialektikos, that is, knowledgeable in the art of dialegesthai, in other words, most capable of telling (legein/legesthai) being as it is in the light of the good (to agathon), that he will be most perfectly anthrôpos (man in the sense of "human being"), and thus, most apt to govern his fellow-men toward what is best for them, individually and collectively.
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Dialektikos (adjective; pl. dialektikoi) (modified May 8, 2021): this is the adjective derived from dialegesthai to describe one who is versed in the art of dialegesthai, the ability to use logos within the framework of dialogos (“dialogue”) in an efficient way making it possible to reach truth without being trapped by words and the tricks of rhetoric. Used as a substantive under the feminine form hè dialektikè (sc. technè), it refers to the practice of one who is dialektilos (see for instance Republic, VII, 534e3), and is diversely described as a poreia (journey, course) (Republic VII, 532b4), a methodos (investigation, pursuit, method) (Republic VII, 533c7) or an epistèmè (knowledge) (Sophist, 253d2). The usual translation as "dialectic" is misleading, especially after Hegel and Marx among others, in so far as this word has taken in English connotations which have nothing to do with what Plato had in mind in using it.
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Dialogos (noun): rather than the noun, rare in the dialogues (9 occurrences only in all the dialogues), Plato prefers the expression to dialegesthai, making a substantive of the verb by adding a neuter article in front of the infinitive (literally “the [fact of] dialoguing”), which stresses the fact that it is an activity being practiced over time, while the noun describes this activity as such without reference to time.
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Dianoeisthai (verb): verb derived from nous (see this word) through the verb noein, which describes the activity of the nous and means “to perceive by the mind, think, reflect, conceive”. The addition of the prefix dia- does not fundamentally change the meaning, introducing only the idea of a progress “through” thoughts occurring in turn and leading to one another, and the move to the middle (noeisthai in place of noein) stresses the fact that the subject is personally involved in the action, which takes place within one’s own mind. In the Theaetetus, Socrates defines to dianoeisthai (“the [fact of] thinking”) as “a speech (logon) that the soul itself conducts from beginning to end with itself on what it examines” (Theaetetus, 189e6-7), suggesting that even thought is dependent on words.
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Dianoia (noun): this is the name of activity derived from the verb dianoeisthai. The stranger from Elea, in the Sophist, defines dianoia in the following way: “Thus dianoia and logos[are] the same: except that the inner dialogue (dialogos) of the soul with itself without the production of sound, this very [thing] has been called by us dianoia (“thought”) […] On the other hand, the flux coming from it through the mouth accompanied by noise is called logos” (Sophist, 263e3-8). This definition is close enough to the definition of dianoeisthai given by Socrates in the Theaetetus (see previous entry), with the difference that the stranger defines simultaneously logos and dianoia while Socrates, after having defined to dianoeisthai as a logos of the soul with itself, later suggests as one possible definition of logosthe [fact of] making clear one’s own dianoia through sound by means of verbal expressions and words” (Theaetetus, 206d1-2), thus ending in a vicious circle (dianoia is a kind of logos, which is a way of expressing dianoia).
Dianoia is also the name Socrates gives to the pathèma (see this word) associated with the first segment of the intelligible in the analogy of the line at the end of book VI of the Republic, the one indeed where we stay prisoner of words.
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Dikč (noun): “justice”. In its primary meaning, dike designates the “custom/usage” determining the “manner of behaving”, and thus “justice” as the respect of this usage; from this primary meaning stem a series of meanings designating, depending upon the context, everything revolving around what serves to enforce justice, leading to the meanings of “lawsuit, trial”, “tribunal, court of law”, “judgment”, and lastly “penalty, atonement, satisfaction”. When written with a capital « D », Dikè designates Justice personified.
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Dikaios (adjective): « just ». This is the adjective derived from dikè. As a substantive in the expression to dikaion, it designates “the just” as what one who wants to be just must seek to accomplish. The subtitle of the Republic is peri dikaion (“about the just”) and the purpose of Plato in this dialogue is to make us understand through the voice of Socrates that justice is not only a social virtue regulating relations between people, but also an “inner” virtue regulating relations between the various parts of the soul uncovered in the dialogue (see the entry about psuchè). It is in the end inner harmony of the tripartite soul as a prerequisite for social harmony between souls. Socrates also talks about justice as the health of the soul. As such, it may be regarded as the “idea(l)” (idea) of the incarnate soul and, since Socrates considers that “the soul is man” (Alcibiades, 130c6), as the “idea(l) (idea) of Man.
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Dikaiosunč (noun): « justice ». Noun formed by adding to the adjective dikaios (“just”) the suffix -sunè referring to the quality implied by the suffixed adjective. Dikaiosunè is the quality, the “virtue” of a person seeking to dikaion (“the just”) in one’s behavior. At Republic IV, 433a8-9, Socrates defines justice as the fact of  “doing one’s own business and not be a meddlesome busybody”, a definition which must be understood in the light of what was said earlier on the origin of cities: man is an animal meant to live in society, which allows him to develop a logos; the framework of social life is the polis (“City/State”), built under the assumption that distributing tasks among individuals is more efficient than letting each one take care of all one’s needs (food, clothing, housing…) and should lead to a more pleasant life for all. Thus, the duty of each politès (“citizen”), especially toward one’s fellow-citizens, is to accomplish the task which was assigned to him in the sharing of tasks and to let the others take care of their own, since, in principle, the sharing has been made taking into account each one’s capabilities, be they a gift of nature or the result of adequate training building upon natural predispositions. This definition does not contradict the one I gave in the previous entry when talking about inner harmony as foundation for social harmony: social harmony is precisely the fact that each one properly plays one’s part in the organization of the city and the prerequisite for this is that he be able in the first place to keep at their proper place each part of one’s soul.
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Doxa (noun): name of activity derived from the verb dokein meaning “to think (in the sense this verb has in a phrase such as “I think you are right”), pretend, suppose”. Doxa is “opinion” as opposed to knowledge (epistèmè). But opinion is not necessarily wrong, it only lacks the line of reasoning which might make it certain and no longer open to change. The end of the Meno focuses on a comparison between knowledge and true/right opinion (alèthès/ orthè doxa) after the experiment with Meno’s slave boy on a theorem of geometry (the doubling of a square) has experimentally shown the difference between opinion (the first answer of the slave, which Socrates has no difficulty proving wrong) and knowledge (the knowledge of the one having understood the demonstration of the theorem used as an example, who will never again change one’s mind on the issue), and Socrates, once again based on experience, forces Meno, a pragmatic who has no interest in abstract speculations, to admit that, from the mere standpoint of results, there is no difference between knowledge and right opinion, using the example of the road to Larissa (a comparison between a guide knowing the road to Larissa and another one who, not knowing it, nonetheless leads travelers there), an example which, with Meno as the interlocutor, takes an peculiar flavor: indeed, Meno is a historical character who was in command of a contingent of Thessalian soldiers from Larissa who joined the army several Greek cities had decided to send in Asia Minor to support Cyrus the Younger in his attempt to oust his brother Artaxerxes from the throne of Persia; Xenophon accompanied this army and he relates the story of this expedition in his work, the Anabasis, and what he relates is how, after the battle of Cunaxa, where Cyrus was killed, and the capture and execution of the Greek generals by the Persians (except Meno, who might have helped the Persians capture the Greek generals after the battle playing the middle man in the organization of negotiations), he took the lead of the Greek soldiers and managed to bring them back to Greece in what is known as the Retreat of the Ten Thousand, finding the way home in hostile territory, without maps, over several thousand miles; and what Xenophon did, to find the way to Athens without knowing it, is what Meno should have done, and didn’t do, to bring back to Larissa the soldiers he was in charge of. Thus, it is based on an actual experience involving the road to Larissa, that of Xenophon, that Plato’s Socrates proves that right opinion is as good as knowledge from the standpoint of results (Socrates is supposed to dialogue with Meno before the Retreat of the Ten Thousand, since Meno stayed in Persia, trying to win the favor of the Persian general Tissaphernes, but ended up in jail and died within the year after the battle of Cunaxa, but all the readers of Plato’s dialogue, written years after these events, knew the story of Xenophon).
When, recalling the analogy of the line toward the end of book VII of the Republic (Republic VII, 533e7-534a8), Socrates associates doxa (“opinion”) to the two segments of the visible and noesis (“thought”, see this word) to the two segments of the intelligible, he does not mean to suggest that the material and sensible world is open only to opinion (doxa) and that only the “world” of pure intelligible beings not perceptible through senses (the beautiful, the just, the good…) is open to thought (noesis), but that there are two ways of envisioning what the senses can grasp, either as exclusively sensible (and thus constantly changing) and this can only lead to opinions about them, or as open to intelligibility with the help of logos and, thinking (noein) about them this way, one might get a chance to make them intelligible (noèta) and to understand them (with no guarantee though to reach that point). And conversely, one may refuse, as the “sons of the earth” (materialists) of the Sophist do (see Sophist, 246a8-b3 and, for the expression “son of the earth” (gènenès), Sophist, 248c2), to consider that purely abstract notions such as “beautiful”, “good”, “just” and so on, are “something” (ti) by themselves (auta, see entry on autos), distinct from what they are applied to, and in such case, one can only have opinions about them (see the discussion on knowledge and opinion ending book V of the Republic, starting at Republic V, 475e3), or admit that such words refer to something independent of what they are applied to, to an idea (see this word), and, in so doing, one might get a chance to make them intelligible and to reach knowledge (epistèmè) about them.
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Dunamis (noun; pl. dunameis): substantive derived from the verb dunasthai meaning “to be able to”. The usual meaning is “power, capacity, capability”. Aristotle uses this word in the sense of “potentiality” in opposition to “actuality”, for which he uses the word energeia, formed on the word ergon (“work, deed, action”) by adjunction of the prefix en- (“in, within”), which designates the quality (ending -ia) of what is “in deed” as opposed to only “potential”. This meaning is already present in Plato, for instance when, at Sophist, 247e4, he defines ta onta (“beings”) as being nothing more than dunamis: what he means by this is that, of whatever is said to “be”, that is, of any “being”, we have yet said nothing so long as we don’t add what it is (to ti esti), its “beingness (ousia, see this word)”, so that it is only “potentially” something, waiting for a predicative expression which will qualify it. In other word as a “being (on)” without further qualification, as the “subject” of a phrase of the form “x is a”, as this x, it is nothing specific yet so long as an a has not been specified, it is yet only “potentially” an a.
At Republic V, 477c1-d6, Socrates explains that, to him, a dunamis is characterized by what it acts upon (eph’ hôi esti, literally “on what it is”) and what it accomplishes (ho apergazetai), mentioning sight and hearing as examples of dunameis. It is interesting to relate the words pragma (see this word), dunamis and pathèma (see this word): a pragma is what possesses a dunamis allowing it to cause a pathèma in something else, that is, to act (prattein, at the root of pragma) in a way which “affects” (paschein, at the root of pathèma) something else. But the same pragma may possess several dunameis affecting different things, for instance a dunamis affecting sight, another affecting hearing, and so on, and besides, the affection produced by the same pragma may differ from one to another: for instance, one psuchè (“soul”) affected by an image presented to it by sight may think that what it sees is all there is to know about the pragma of which it is only an image, while another psuchè understands that what it sees is only an image; in such case the pathèma is different from the one to the other, and thus also the dunamis causing it (this is what the analogy of the line at the end of book VI of the Republic is all about).
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Eidos (noun; pl. eidè) (modified April 19, 2021): a word derived from a root meaning “to see”, which is almost identical to the present aorist eidon (“I see” or “I saw”) of the verb horan (“to see”). Thus, the eidos is originally what is there to be seen, the “appearance” for human sight. From this primary meaning, the word takes the secondary sense of “species” (all the things having the same outward general appearance), and eventually of “kind”, or “form” (the “appearance” limited to its outward boundaries). For Plato, the eidos, in the secondary sense, is what is common to all the things having the same name (Republic, X, 596a6-7), whether it be a physical being or an abstract concept. And it is this move from the primary individual sense (the “appearance” of a single pragma), in which eidos refers to what could be reproduced in an eikôn (“image”), to the secondary (collective) sense grounded in the resemblance of multiple “originals” which is key, not the move from criteria of resemblance taken from the visible to criteria of resemblance taken from the intelligible, because it is what makes the attribution of names possible and in the end, along with it, the logos and most importantly to dialegesthai (the practice of dialog). In the analogy of the line, in book VI of the Republic, Plato has Socrates talk about horômena eidè (“visible appearances”, 510d5) and a few lines later, of noèton eidos (“intelligible appearance”, 511a3). Thus, there is continuity of meaning from sensible to intelligible and it is the reason why he may use the same word in both cases. Indeed, it is to make us understand this continuity that he takes the risk of using the same word. And what must be properly understood is that, in either case, an eidos remains an “appearance”, that is, a perception conditioned by the capabilities dans limits of what makes this perception possible, be it one of the sense organs or the intelligence, of which we have no way to be sure it reveals the whole of what it is an eidos. And in both cases, eidos may be understood in two ways, depending on whether one adopts an objective (the eidos independent of any specific observer) or subjective (the eidos as perceived by a specific observer with his own capabilities and limits at the time of observation) point of view about it: from an objective point of view, the visible eidos is what is visible (horaton) for human eyes in the abstract, not what is seen (horômenon) by specific human eyes; the intelligible eidos is what is intelligible (noèton) by the mind (nous) in the abstract, not what is understood (noumenon) by a specific individual ; from a subjective standpoint, the eidos is what is perceived by a specific person at a specific moment of one’s physical and intellectual development with the defects of one’s organs of perception (for instance being color-blind or short-sighted regarding sight, or mentally retarded regarding intelligence) and this eidos may thus evolve over time from the one this person associates with a given word he is learning when still an infant, based exclusively on visible criteria to the one he associates  with that same word at the end of a life of study and reflection having allowed him to uncover criteria of intelligibility no longer dependent upon the visible appearance of what is under investigation and thus to reach its idea. It is this “evolutive” character of our knowledge, which implies a learning process (see gignôskein) spreading over time and implying change that the Elean Stranger uses against those he names “friends of eidè” and opposes to those he names “sons of the earth”, trying to make them understand that, if the refuse ousia (“beingness”) to everything which changes, they make knowledge impossible for men (see Sophist, 245e8-249d5, and especially 248d4-e5). Thus, the key breakthrough is not between visible eidè and intelligible eidè, but between eikones (“images/resemblances”) and eidè, as Socrates attempts to make us understand in the analogy of the line when he describes the process associated with the second segment of the intelligible as “building, without the images (eikonôn)[revolving] around that, with the appearances themselves its own approach (methodos) through them” (Republic, VI, 510b7-9 ), eidè implying at this point, where we reach the ultimate stage of the intelligible, intelligible eidè, that is, ideai. An eikon (“image/resemblance”) is always image/resemblance of a unique subject while an eidos implies generalization to a plurality of subjects resembling one another from a certain standpoint, which requires to ignore space and time and to “still” that which, at the individual level, keeps changing all the time, thus making logos possible, that is, at the same time speech (and thus dialogue) and reasoning.
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Eikasia (noun): “representation, comparison, conjecture”; substantive derived from the verb eoikenai meaning “to be/look like, seem” through the verb eikazein, “to represent by an image or likeness, form a conjecture”. This is the name Socrates gives to the pathèma (see this word) associated with the first segment of the visible in the analogy of the line at the end of book VI of the Republic, the one where we stay prisoner of the images provided by sight without realizing they are always only images. Thus, eikasia in this sense is the state, the quality (ending with -ia), of who lives in a world of images (eikones see next entry) taking them for reality, who develops a representation of the world around based on what is only images, without seeking more than what sight captures; it is, in the language of the allegory of the cave, the prisoner taking the shadows of the statues for “the true (to alèthes)” (Republic VII, 515c1-2).
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Eikôn (noun; pl. eikones): “image, likeness”. Like the previous one, this word is derived from the verb eoikenai, which means that it stresses the idea of likeness, not solely visual. This is the concept Socrates uses in the analogy of the line, at the end of book VI of the Republic, to differentiate the two segments of the visible, giving as examples of eikones shadows and reflections in bodies of water or other reflecting surfaces. But the reading in parallel of the analogy of the line and the allegory of the cave shows that what takes the place of reflections in the allegory inside the cave, image of the visible/sensible world, is the echo of the voice of the bearers of statues, that is, audible “reflections”, which nonetheless are sorts of eikones of those who utter these words, it that they give a non-visual “image” of them.
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Einai (verb; present part. masc. ôn, fem. ousa, neuter on, neuter pl. onta): “to be”. For Plato, this word is only a function word linking a subject (an on (“being”)) and a predicative expression (a “beingness (ousia)”, a “what it is (ti esti)”). When Plato uses this verb without a predicative expression, the context should always be used to determine which one(s) are implied and should be assumed. Thus, if he speaks of “being” in the intelligible realm, it implies being intelligible, while if it is in the visible realm, it implies being visible. And when “to be (einai)” is opposed to “to become (gignesthai)”, it doesn’t mean that what becomes doesn’t “exist”, but that he opposes what is stable, immutable, everlasting… to what is changing, moving, unstable, temporary… Thus for instance when, in the parallel between good and sun toward the end of book VI of the Republic, Socrates says that, under the effect of the good (to agathon), everything which is known by us is not only known, but also gets from it to einai te kai tèn ousian (“being and beingness”, 509b6-8) in the same way as all which is lighted and made visible by the sun gets also from it tèn genesin kai auxèn kai trophèn (“becoming and growth and nourishment”, 509b2-4), obviously he doesn’t mean, when attributing to einai to the good, that it is the productive cause of the material existence of all we know, but only that it is the cause of their “being intelligible”, of their intelligibility, since to really understand anything is for him to understand its relation to the good, in what way it may be good for us. And the ousia following the einai is precisely the specific “value” of what is under consideration regarding the good. And, in the parallel, the einai on the side of the good answers the genesin (“becoming”) on the side of the sun, in the same way the ousia, that is, the specific value of what it is with regard to the good and no longer solely the fact of “being”, the einai, on the side of the good answers the growth resulting from nourishment, which gives each thing its specific consistency, and no longer a simple abstract and undetermined “becoming”, on the side of the sun.
If Plato distinguished two meanings for the verb einai, it is not an existential meaning from a copulative one, as is often said, but a meaning implying identity in which “a esti b” means “a = b” (as for instance in “the person talking at the tribune is Alcibiades”) from a meaning implying only association, in which a and b remain distinct from one another but share something in common, a “participating” (metechon) in the idea of b (as for instance in “Alcibiades is beautiful”, which doesn’t mean that Alcibiades is the beautiful, but that he participates in the idea of the beautiful). As for the supposed “existential” meaning einai (“to be”) might have when used alone, without an explicit predicative expression, it is but a lure because, short of any explicit predicative expression it can have meaning only in assuming some implicit ones (such as “material”, or “sensible”, or on the contrary “incorporeal”), which opens the door to all kinds of sophisms, as Plato brilliantly demonstrates by example in the Parmenides.
And in the same way einai is the least meaningful verb due to the fact that it may apply to absolutely anything since, as soon as I think about anything, it “is” at least a thought in my mind an as soon as I utter any word, it “is” at least a word, the least significant predicate is hen (“un”), since to think about anything is to isolate it in thought and give it in this way a “unity” at least from a conceptual standpoint by making it one subject, one on (“being”). This is the reason why Parmenides’ ravings in the dialogue bearing his name can lead nowhere, since they take as starting points only these two words having no specific meaning. The question about what “is” and what “is not” is meaningless. The only meaningful question is to figure out whether the combinations of words we make up adequately reflect what they purport to refer to, which can only be decided in the end based on the efficiency of these combinations in dialogues meant to lead to a result in action.
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Epistèmè (noun): “knowledge”, rather than “science”, either in opposition to doxa (“opinion”) or in opposition to technè, which rather refers to a “technical” (English word derived from technè) know-how. The etymology of the word suggests the idea of “standing above”, that is, of “dominating” the subject-matter, master it and have a comprehensive view of it. Epistèmè is also the name used by Socrates, in his recall of the analogy of the line toward the end of book VII of the Republic, to replace noèsis as the name of the pathèma (see this word) associated with the second segment of the intelligible (Republic VII, 533e8), which tends to make epistèmè something which, if at all accessible to a human being, remains incommunicable and beyond words, since words would make us fall back in the first segment of the intelligible, that of dianoia. This is the reason why sophia (“wisdom”, see this word) is out of reach of human beings, who can only strive for it and be in love with it (philoosophoi), without ever being sure of having reached it. The Theaetetus is a lengthy failed attempt to come up with a definition of epistèmè. Failed because rather than starting from an investigation of logos (which will be the topic of the ensuing  Sophist), which is the unavoidable tool for the search for epistèmè, the discussion raises the issue of logos, understood in various ways that it attempts to define, only at the end, after other attempts at defining epistèmè have failed, trying to understand how logos might be something added to something else, namely opinion (doxa), already described as a logos (Theaetetus, 190a5), to transform it into knowledge.
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Epithumia (noun; pl. epithumiai): “desire, passion, yearning, appetite” in all domains, not only sexual. In the analysis of the various parts of the psuchè (“soul”) by Socrates in book IV of the Republic, this word, used in the plural (epithumiai), describes one of its parts, also called epithumètikon (“desiring” part). In opposition to the “reasoning” part (logistikon) which is principle of unity, the desiring part is principle of multiplicity by virtue of the multiplicity of desires (hunger, thirst, sexual appetite, and so on). If the word epithumia may be used for all sorts of desires, including intellectual ones, in the analysis of the psuchè, the “desires” associated with the epithumètikon part are all the desires stemming from the body and the corporeal, “animal” nature of human beings.
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Erôs (noun): “love, sexual passion” and sometimes “desire” in general. It is also the name of a Greek deity described by Plato as a daimôn in its genealogy as related by Diotima in the Symposium, that is, a deity intermediate between gods proper (theoi) and human beings. For Plato, erôs in a not exclusively sexual sense, is the primary moving force of the human psuchè (“soul”), driving it to establish relations with others especially through dialogos, which starts with the urge to ask questions (erôtan) to others. Even if both words, erôs, whose genitive is erôtos, and the verb erôtan (“to ask questions, question”, as opposed to eran meaning “to love”) don’t stem from the same root, the similarity between both words couldn’t not strike Plato, who plays on it in the fanciful etymologies of the Cratylus, associating Erôs as name of a god to hèros (“hero” in the Greek sense relating to the heroes of mythology), whom he considers half-gods before pointing at the similarity of the word with erôtan (“to question”) and eirein (“to talk”), which he equates to legein, from which logos stems (Cratylus, 398c5-d8). In the Symposium, Socrates, recounting words he heard from Diotima, describes the way this erôs may raise the soul from the exclusively carnal love aroused by the contemplation of one beautiful body all the way up to the idea of the beautiful (which is, in a first stage at least, the sensible dimension of the good).
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Genos (noun; pl. genè): this word, derived from the verb gignesthai(“to be born, become”, see next entry) in its aorist form genesthai, means in its primary sense “family”, that is, a group sharing a common origin: “biological” family strictly speaking, sometimes limited to the children or to the direct descent, or, in a broader sense, all the member of a same “tribe”, “clan” or “race”, before taking analogically the sense of “class”, sort”, “kind” or “genus” (its Latin counterpart). Aristotle opposes the genos to its constituent eidè (translated as “species” in this case). What should be noted about these two words is that genos designates “things” associated together due to their common origin while eidos, derived from a root meaning “to see”, associates “things” based on their common appearance. And if both have an origin in the sensible realm (“to be born” and “to see” are phenomena of the sensible world), both enlarge their meaning toward the abstract and intelligible realm.
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Gignesthai (verb): this verb has two main ranges of meaning: as a punctive (non-durative) verb, its primary meaning is “to be born” and as a durative verb, its primary meaning is “to become”; the meaning “to be born” leads to the meaning “to occur” for any kind of event. Besides, at the aorist, it takes the sense of “to be” (“to be born” is “to be” once born and the moment of birth has passed). This being said, for Plato, this verb is often opposed to einai (“to be”) to distinguish what is subject to change and becoming to what doesn’t change and stays always the same.
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Gignôskein (verb) (added April 19, 2021): the usual translation of this verb is “to know”, as is the case with the well-known Delphic precept gnôthi sauton (quoted under this form, in which gnôthi is the second person of the singular of the active imperative aorist of gignôskein, at Alcibiades, 124a8-b1, Protagoras, 343b3 and Philebus, 48c10), usually translated as “Know thyself”. But gignôskein is an intensive verb featuring reduplication (the pure root gnô- reduplicated in the initial gi-) and an ending in -skô expressing the repetition of an activity the accomplishment of which requires efforts, and thus its primary meaning is “to learn/get/come to know” so that a better translation of gnôthi sauton is “Get to know thyself”, and it is obviously in this sense that Socrates understands it when making it his own. This primary sense of ginôskein is also found in the derived substantive gnosis, which, besides the meaning “knowledge”, also has the meaning “inquiry” or “investigation (especially judicial)”. This primary meaning of gignôskein is important as far as Plato is concerned in that it highlights the fact that knowledge (gnosis in a sense close to that of epistèmè) is the result of a process unfolding over time and implies changes in the apprehension of what one tries to know through eidè and ideai (see these two words) which don’t “fall” upon us from who knows which “heaven” of pure ideas inducing an instantaneously “perfect” and definitive grasping, but unveil progressively, first through perceptions of the senses, then through intelligence (nous), evolving for each person over time with no guarantee that she will ever reach perfect knowledge, nor that such knowledge be accessible to human beings. It is the change implied by the thought process leading to knowledge that the Elean Stranger uses in the Sophist against those he calls “friends of eidè” to make them understand that refusing ousia (“beingness”) to everything which changes amounts to denying human beings the ability to know (see Sophist, 245e8-249d5, and especially 248d4-e5).

Gunè (noun): “woman” as opposed to anèr (“man”, see this word), that is, taking sex into account. For Plato, there is no difference in nature between men and women, both being endowed with logos, and thus being anthrôpoi (“human beings”). The only difference is that they play a different part in the generation of children, and this difference is relevant only regarding the generation of children, not regarding all other tasks that anthrôpoi, male as well as female, are called to accomplish in the city through the sharing of collective tasks, including the role of warrior (see Republic V, 449a1-457b6).
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Heteros (pronoun and adjective): “other (of two), other, different”. Under the form thateron, contraction of the neutral used as a substantive to heteron (“the other”), this word plays a major role in some dialogues, especially the Sophist and the Timaeus, in opposition to tauton (“the same”, see this word). In the Sophist, the Elean Stranger explains that to mè on (“the not being/being not”) simply means “the (being) other” and not “that which is not at all”, since to him as to Plato, “to be” (einai) necessarily implies a predicative expression, a “beingness", a something which the subject is (explicit or implicit) and so, similarly, mè einai (“to be not”) implies a something the subject is not, without this implying that it is nothing at all, but only that it is something else. For the role of the pair tauton/thatreron (“same/other”) in the Timaeus, see the entry on autos.
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Homologein (verb): etymologically “to say (legein) the same (homos) thing”, that is, “to agree, concede”. For Plato, the agreement implied by this verb is not limited to the agreement between persons, but starts with an agreement with oneself over time, that is, to always say the same thing”, so long as it is not the result of stubbornness and one accepts to change opinion if discussion and shared experience lead to reappraise one’s prior opinions. The specificity of the one who knows is to always say the same thing. So long as, on a given subject, one may be led to change his mind, it means that this person does not know and only has an opinion (doxa). The search for an agreement between interlocutors who subject their opinions to criticism by the others and share their experience, accepting to change their minds if the discussion requires it, is the basis of the Socratic “method”, since it is through dialogue only that logos gets its meaning.
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Homologia (noun): substantive derived from the previous one: “agreement.”
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Horan (verb; aorist idein, perfect eidenai): “to see”, and in the perfect used as a present, “to know” (“I have seen”, thus “I know”). Various inflexions of this word, depending on tense, are built on different roots (as for instance “to go” in English), the root of idein being the same as that of the Latin videre (“to see”) and the French “voir”, derived from it. This root is found in idea (see this word), and that of eidenai, which is a variant of it, in eidos (see this word).
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Horaton (verbal adjective, neuter of horatos): in Greek, verbal adjectives ending with -tos (-ton in the neuter) express a possibility, like English adjective ending with -able (capable, unbelievable, thinkable…) or -ible (possible, perceptible, perfectible…), but some of them, in some contexts, may be equivalent to a mere passive past participle. Here, horaton, verbal adjective of the verb horan (“to see”), means “visible”, and is often opposed by Plato to noèton (see this word), verbal adjective of the verb noein (“to think”), most often translated as “intelligible”. These two adjectives are used by Socrates to qualify the two segments resulting from the first split in the analogy of the line. There, he also uses, aside from these two verbal adjectives, the two past participles horômenon (“seen”) and nooumenon (“though”), here again, not merely for stylistic considerations to avoid repetition, but based on the standpoint which is his in each case (which shows by the way that, in this case, the verbal adjective should not be understood as mere past participles): talking of horaton (“visible”) or noèton (“intelligible”) is to consider things from the standpoint of the pragma (see this word) capable of affecting sight or our mind directly and to attribute to it a property which is precisely the ability to affect sight, for what is said to be horaton (“visible”), or mind, for what is said to be noèton (“intelligible”), independently of the fact that there actually is anybody affected (something may be “visible”, even if nobody ever sees it), while talking about horômenon (“seen”) or nooumenon  (“thought”) is looking at things from the standpoint of the affected subject and referring to their actual affections.
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Hupothesis (noun; pl. hupotheseis): etymologically, “what is put (themenos) under (hupo)”. Originally, this word does not have the meaning of its transcription into English, that of something “uncertain”, “conjectural”, which is found in the adjective “hypothetical” and in its equivalent of Latin origin, “supposition”, but on the contrary, indicates what serves as a basis, as a support, as a firm starting point from where to build a reasoning “upon”. The examples of hupotheseis given by Socrates in the analogy of the line, at the end of book VI of the Republic, though in a geometrical context, “the even and odd, figures and the three appearances/sorts of angles” (VI, 510c4-5), are not, for that matter, “hypotheses” in the modern sense, but rather initial prerequisite data from which a problem can be formulated.
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Hupotithenai (verb): it is the verb from which the previous word is derived; its primary meaning is “to put/place under”, and by extension, with the idea of “placing” something “under” (that is, before) the eyes of somebody, “to set before (someone)” and from there “to suggest” and eventually “to assume, suppose”, from which the meaning “assumption, supposition” of hupothesis derives, aside from the meaning “thing placed under, base, support”.
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Idea (noun; pl. ideai): substantive derived from the root of the aorist idein of the verb horan (“to see”), with a meaning close to that of eidos (see this word), that is, “appearance”, in a first time visible, a meaning in which Plato sometimes employs it, for instance at II, 380d2, where idea alternates with eidos and morphè, (“form/shape”, another word whose meaning is close to that of eidos and idea), or at Republic IX, 588c4 and c7, or else at Phaedo, 109b6, where the final myth refers to the idea (“form, aspect”) of the earth. Idea is less frequent in the dialogues than eidos (97 occurrences of idea compared to 406 occurrences of eidos). In some contexts, Plato uses idea designate a specific kind of eidè referring to nothing sensible, but only to intelligibility principles, what he calls noèton eidos (“intelligible eidos”, Republic VI, 511a3 ) in the analogy of the line, as opposed to horômena eidè (“visible eidè), Republic VI, 510d5). If, in this analogy, Socrates does not use the word idea, it is because, at this stage of the discussion, his objective is to establish a parallel between the visible/sensible order and the intelligible order and that, in the same way he exhibits a unique principle, that of the relation between image/resemblance (eikôn) and original, to justify the splitting in two of each segment, that of the visible and that of the intelligible, he wants to insist on the fact that in both orders there are eidè and that there is continuity from an order to the other, intelligible as well as visible eidè being only “appearances” for us, human beings, not the pragmata themselves (auta). But when he describes the pathèma associated with the second segment of the intelligible as the one where one relies only on eidè, it must be understood that, since we are in the intelligible, these eidè are intelligible eidè, hence ideai and no longer visible eidè. It is only after having made it clear, through the allegory of the cave, which follows the analogy of the line at the beginning of book VII of the Republic, and its recall toward the end of this same book (Republic VII, 532a, sq.), that everything which is visible inside the cave, starting with anthrôpoi (“human beings”, Republic VII, 516a7), or rather their individual soul (to which the word anthrôpoi refers in the allegory, always used in the plural), but also including animals (Republic VII, 532a3) and plants  (Republic VII, 532b9), can be found individually outside the cave, which means that there are intelligibility principles, that is, intelligible eidè, ideai of the material creatures of the visible/sensible order considered individually, that, at the beginning of the last book of the Republic, book X, through examples taken in the realm of human craftmanship (tables and beds, as it happens), thus easier to grasp that divine productions, he confirms that even of this, there are ideai, in the discussion about the three kinds of beds, after having introduced this discussion stating that “the usual method” of human beings is “to assume a certain eidos, unique in each case, for each plurality [they] assign the same name to (Republic X, 596a6-7) and having stated in the allegory of the cave that the chained prisoners give names to the shadows (Republic VII, 515b4-5), that is, to the visible appearance of material realities, which suggests that the eidos that we associate to things bearing the same name is not necessarily an abstract principle of intelligibility but starts being a mere visual appearance. The two examples he takes, trapeza (“table”) and klinè (”bed”) indeed exhibit successively a name, trapeza (“table”) assigned in the basis of an horomenon eidos (“visible  eidos”) since etymologically, trapeza means “having four feet” and thus refers to the visual appearance of a table (which is not even specific to a table since a bed too may have four feet), and a name, klinè, assigned on the basis of a noèton eidos (“intelligible eidos”) since klinè is the substantive derived from the verb klinein meaning “to lean/lie”, which means that the word points at the function of the piece of furniture so named, to its purpose (allow to lie on it), to what makes it possible to manufacture a bed without having to mention its external appearance, simply deducing it from the purpose of such a piece of furniture. And at this point, Socrates indeed refers to the idea of bed as what the bed manufacturer fixes his “eyes” on, though none of the craftsmen made it (Republic X, 596b6-10). If, of something material, there is not only a visible eidos, but also an intelligible idea, of a pure intelligible, there is only an idea, even if it can still be referred to as an eidos since an idea is a specific kind of eidè. This is the reason why Plato’s Socrates talks about the idea of the good (hè tou agathou idea), never about the eidos of the good. Such an idea, of a material thing as well as of a pure intelligible, takes for us the form of logoi yet is not these logoi, which may differ from a person to another or from a language to another. Thus, for instance, the idea of bed may be described by a sentence such as this one: “a bed is a piece of furniture intended for one or several persons to lie down on it to rest or sleep.” It can immediately be seen that the question whether the idea of bed is a bed is meaningless since the purpose is not to lie on an idea understood this way, and that the so-called “argument of the third man” suggesting that an idea shared by the manufactured beds and the idea of bed would be required to justify using the same name for both is meaningless and exhibits an inability to disregard visible images when thinking about anything and to grasp the difference between the realm of the visible and the realm of the intelligible displayed in logos.
In the dual process of gathering and dividing described by Socrates in the Phaedrus (Phaedrus, 265d3-266b1), that he presents as the tool of the one he calls dialektikos, the gathering is made “toward a unique idea” (eis mian idean) while divisions are made “according to eidè” (kat’ eidè) with a risk of not respecting the natural joints. This suggests that, while the divisions may be made anyway, for instance by prisoners chained since birth having as sole criteria of distinction for giving names the shadows, that is, the visible appearance of material realities, the gathering purports to reach (eis”toward”) the intelligible idea and is not completed so long as it has not reached this objective and thus not understood what makes an instance of what is under consideration a “good” instance of that, which can only be determined with regard to its purpose.
This manner of understanding idea is consistent with the meaning its import into English as the word “idea” has taken.
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Klinè (noun): “bed”. This word would not have its place in this lexicon had it not been used by Socrates, along with trapeza (“table”), in book X of the Republic, as example in the analysis known as “the three kinds of beds” which is key to the understanding of the words eidos and idea. What is important in the choice of examples, and which is impossible to reproduce in English without betraying the Greek, is that Socrates starts his explanations with two examples of items of furniture (that is, material objects, not even living, not even produced by nature, but manufactured by human beings), klinè (“bed”) and trapeza (“table”), one of which, klinè, names what it points at with a word derived from the verb klinein, meaning “to lean, lie down, recline, lie upon (something)”, that is, with a word making its function known (a klinè is what we can klinein on, “lie upon”), while the other, trapeza (“table”), whose etymological meaning is “having four feet/legs”, names what it refers to with a word describing its external appearance, its visible structure. Now, in what follows, after having noticed that the manufacturers of these items of furniture work with the idea of what they manufacture in their mind (suggesting that there is an idea even of such manufactured objects), he keeps only one of the two examples, klinè, that is, the one for which the name points at the function, the purpose of the object, helps us understand what this object is and in view of what it may be “good” to us. To have four feet tells us how the piece of furniture is structured, not what it may be used for and, incidentally, a bed too may have four legs. These seemingly insignificant choices, which do not strike the scholars I had access to, are nonetheless key to help us understand what Plato means by idea. To keep this import in English, rather than slavishly translating Plato’s Greek, klinè might be replaced, rather than translated, by “seat” (it doesn’t matter whether the noun is derived from the verb or the other way around, the fact is the word is both a noun and a verb and thus tells something about the use of the thing by that name) and trapeza replaced, rather than translated, by “tripod”.
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Kosmos (noun): the primary meaning of this word is “order” (as in “put things in order”, not “give an order”), and more specifically “good order, good behavior”. It is in reference to the fact that the Universe seems to obey laws and give an example of good order that it is sometimes called “Cosmos”, meaning a well ordered Universe. In the last tetralogy, the Timaeus describes this “order” of the Universe as a model for the work that awaits lawmakers in charge of bringing order in cities.
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Krisis (noun): substantive derived from the verb krinein, “to separate, distinguish, sort, decide, judge”, which refers to the general idea of distinguishing, of making a choice, and may mean “choice”, “decision”, “judgment” in a non-specifically judicial sense as well as in that specifically judicial sense. It is the word used by Hippocrates and his school to refer to the phase or phases of a disease allowing a diagnosis on the disease and the prognosis about its expected issue (recovery or death) and it is at the root of the English word “crisis”.
From this same root stems the adjective kritikos, “able to discern, to judge”, which is at the root of the English words “critic” and “critique”. In the Sophist, the Stranger from Elea conducts successively seven attempts at “defining” the “art (technè)” specific of the sophist through the method of successive dichotomies, which may be put in parallel with the seven tetralogies of the cycle of the dialogues, five in the domain of the acquisitive arts, one in the domain of the arts which the stranger gathers under the general qualification of diakritikè, and eventually one in the domain of the productive arts. In the word diakritikè, the prefix dia- (“through, in the midst of”) strengthens the idea of separation, but we are indeed in the domain of krisis, of discernment, of discrimination. And it is precisely on the occasion of this analysis of the art of the sophist that the Elean Stranger describes a manner of “healing” a “sick” soul (psuchè) suffering from the sickness proper to souls, ignorance, using a method by questions and answers (Sophist, 230b4-d4) which it is impossible not to recognize as the method used by the Socrates of the dialogues. And indeed, as soon as he is finished with describing it, the Stranger hesitates to acknowledge this technique as being that of the sophist, even if, as he says, it resembles it “like a wolf to a dog” (231a6), which reminds us of the Euthydemus, where precisely, the method of Socrates is presented in parallel with that of two caricatural sophists. This discussion of the sophist as “critic” is meant to solicit the “critical” mind, the ability to discern, the judgment (krisis) of the reader so that he may make a distinction between the sophist and the philosopher. It suggests that the sixth step in the progression of the dialogues is the time of krisis and it is indeed at this rank that the Sophist finds its place, as central dialogue of the trilogy of the sixth tetralogy.
The notion of krisis is again at the center of the last tetralogy since the name of its central dialogue is that of a character, Critias, whose name is derived from krisis and that its incompletion, deliberate in my opinion, is precisely the practical test of the discernment of the reader at the end of the training cycle proposed by the dialogues: should Critias be allowed to complete his myth of Atlantis which suggests that the gods are those who settle human affairs (the dialogue is interrupted at the time where “Zeus, the god of gods, who reigns through laws”, is about to talk at the assembly of the gods  he summoned to attempts to restore order in the island of Atlantis), or should we rather listen to old men who “deify” themselves by drawing laws (nomoi) for human beings while climbing the slopes of Mount Ida in Crete, in a dialogue, the Laws, which precisely starts with the word theos (“god”) beginning a question on the origin of laws (“[is it] a god or someone among human beings, in your opinion, strangers, [who] is responsible for the arrangement of laws?” (Laws I, 624a1-2)? For sure, Plato did not invent the name and character of Critias, a historical character who was a cousin of his mother and was for a few months one of the leaders of the government of the Thirty Tyrants, but he is the one who decided to cast it as the “hero” of this dialogue, at this point of his cycle, in a conversation which is the product of his imagination.
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Logistikos (adjective; neuter: logistikon): having to do with reasoning, with reason. Adjective derived from logos through the verb logizesthai which leans make use of one’s logos, of one’s reason, that is “calculate”, both in the mathematical sense of “compute” and in the more general sense of “evaluate a course of actions trying to anticipate their outcome”, “plan.” Under the form of the neuter to logistikon used as a substantive, it is the name of one of the three parts of the tripartite soul presented in book IV of the Republic, the part endowed with reason, corresponding to the charioteer of the image of the winged chariot of the Phaedrus illustrating this tripartition.
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Logos (noun; pl. logoi): this word is rich of a broad range of meaning, all referring to the various manifestations of this defining power of human beings which distinguishes them from all other animals, their ability to produce through speech something having meaning and not limited to mere modulated sounds. No single English word may alone convey the full range of meanings of this Greek word, which even ended up becoming the name of the Son of God in John’s gospel (translated as “Verbum” in Latin, and Word in English, as in “and the Word became flesh”). The whole cycle of the dialogue may be regarded as a long reflection on logos, its mechanics, its power and limits, which is in fact merely a reflection on what makes the specificity of human beings, required to determine what their “perfection (aretè)” is, which can only consist in an optimal use of this defining logos in view of happiness. Thus, logos is at the same time meaningful vocal expression in all its forms (“speech, definition, tale, account, explanation, report…”) and what it manifests, that is, reason, which gives meaning to these words.
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Noein (verb): verb of action derived from the root nous (see this word) meaning “to perceive by the mind (nous), apprehend, understand, think”; there exists several forms of this verb with prefixes, such as dianoeisthai (middle, see this word); ennoein, to have in (en-) the mind” or “to put in one’s own mind”, that is, “to understand”; katanoein, “to understand”, in which the prefix kata- adds a mere idea of completeness (“fully”). The noein as an activity of the mind is often opposed by Plato to the horan (“to see”), an opposition also found between the words derived from these verbs; such as the verbal adjectives noèton (“intelligible”, see this word) and horaton (“visible”, see this word).
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Noèsis (noun): substantive of action derived from the verb noein: “thought”. This is the name Socrates gives to the pathèma (see this word) associated with the second segment of the intelligible in the analogy of the line at the end of book VI of the Republic, in opposition to dianoia, associated with the first segment of the intelligible. When he recalls the analogy toward the end of book VII, Socrates replaces noèsis by epistèmè to name this pathèma and uses noèsis to refer to the two pathèmata of the intelligible as a whole in opposition to doxa (“opinion”, see this word), used to refer to the two pathèmata of the visible as a whole. For the meaning of this opposition, which is not an opposition of objects (sensible and intelligible) but of attitudes of the mind toward sensible and intelligible objects, see the entry on doxa.
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Noèton (verbal adjective, neuter of noètos): verbal adjective of the verb noein (“to think” in the sense of “to make use of one’s mind, of one’s nous”), used to characterize what is fit to be thought as opposed to what is perceptible by the senses. For the opposition between noèton and horaton (“visible”), especially in the analogy of the line, see the entry on horaton.
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Nomos (noun; plural nomoi): “usage, custom, law”. For Plato, nomoi are what allows the organization of social life between human beings as long as they are not all “wise (sophoi)” (in fact, nobody is) nor even philosophoi, and the few who are can’t personally solve all the problems of the others on a case-by-case basis. Good laws are the noblest production of human logos and allow anthrôpoi to bring order (kosmos) in their “cities (poleis)”, which constitute their “universe” of life and which they are responsible for building, using as a model the work of the dèmiourgos creator of the Kosmos which the Universe around them, which also obeys laws, constitutes. It is this notion of laws as the mark of human logos in the world which helps understand the attitude of Socrates toward his condemnation to death, as he justifies it in the Crito: laws made by human beings, and not dictated by gods, may not be perfect and, as a matter of fact, the condemnation to death of Socrates was unjust, but if human beings condition their abiding by the laws upon considerations of personal interest and try to evade them when they become detrimental to them, or rather, to their material belongings and/or their body, it is the end of laws and thus of human reason (logos) in the world, and thus the end of Man, who differs from other animals precisely by the fact of being endowed with logos, and for whom the material body is nothing more than a temporary “housing” for his/her true “being”, which is the psuchè (“soul”).
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Nous (noun): “mind, intelligence/intellect” as a faculty of human beings added to senses to give them one additional access to their environment.
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On (pl. onta; present part. neuter of einai, "to be"): Plato uses this participle preceded by the neuter article in the expression to on (literally “the being”, singular) or ta onta (“the beings”, plural) to refer to what we would nowadays call the “subject”, especially in a grammatical sense (the Greek of Plato’s time had no grammatical metalanguage to refer to the various types of words and their functions in a sentence): to on, the “being”, is the one which is said to “be” in an expression of the form x esti a (“x is a”) and ta onta, “the beings”, potentially refers to everything that can be referred to in such sentences, that is, everything we may isolate in our mind to make it a subject of any sentence, that is, in the end, everything, everything anyway which is on our part object of logos. Thus, words are a kind of onta among other, as the Elean Stranger says in the Sophist (see Sophist, 260a5-6, where he says it of logos as a whole, of which words are the building blocks), since it is always possible to say at least that they “are” words. Thus, to on is not “being, and even less “Being” with a capital “B” (which, by the way, would be to einai, infinitive, and not to on, present participle), which no one is capable of saying what it might “be”, precisely because, so long as no predicative expression is added, einai alone, like “to be” in English, means nothing. Paradoxically, and most likely ironically, one of the very few dictionary style “definitions” found in the dialogues is the one given by the Elean Stranger in the Sophist for einai/onta, which reads as follows: “I declare then that whatever possesses the least power (dunamis) either to act (poiein) upon whatever else of any nature or to suffer (pathein) even in the most trifling way under the slightest one, even if only once, all this [I declare] really to be (einai)”, which he summarizes under the form “for I set up as a definition to define ta onta (neuter plural, that is, the “subjects” of sentences having the general form “x is a”) that it is nothing else but potentiality (dunamis)” (Sophist, 247d8-e3). As it stands, this definition covers absolutely everything and thus distinguishes nothing specific (on the meaning of the final summary, see the entry about dunamis).
Where the ridicule is at its height, despite Plato’s efforts to clarify the meaning of this expression through the words of the Elean Stranger in the Sophist, is about the negative expression to mè on (literally, “the not being”), usually translated as “not-being”, or worse, “Not-Being” with capital letters, referring to no one knows what, even more so than in the case of “being”. The Elean Stranger first tells us that the difficulty is the same with to on and with to mè on (Sophist, 250d5-251a4), which means that to understand the one is to understand the other, and then, he focuses on to mè on. And what he tries to have us understand is that, in the expression toon, the negation doesn’t negates the subject, the on, but the predicative expression which the conjugated form of the verb einai which follows, the esti or equivalent, introduces (or which is implied): x mè esti a doesn’t deny x, doesn’t make it a “not-being”, but on the contrary, introduces it as a subject (at least a grammatical one), thus making it an on, a “being”, regarding which it denies the relevance of the predicative expression a. But to say that x is not a is not to say that x is nothing, but only that it is not a, but might be a host of other things. In short, it “is” other than a. And if “not being” calls for a predicative expression, then “being” calls for one too. An on is a subject “being” (this or that) and a mè on is a subject “not being” (this or that). In either case, a predicative expression is expected, explicit or implicit. The problem is that people don’t agree on the predicative expressions that must be considered implied when einai is used without an explicit one, and thus, they may change from one person to another and depending on the context.
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Onoma (noun; pl. onomata): the primary meaning of the word is “name”, of a person or of a thing. This word is the root of the verb onomazein, meaning “to name, call (something or someone by a specific name)”, used in the allegory of the cave, at the beginning of book VII of the Republic, about the chained prisoners when Socrates says, before describing the freeing of one of them, that “if they were able to dialogue (dialegesthai) with one another, the same [things] being around [again], they would take the habit of giving names (onomazein) to those [things] they see” (Republic VII, 515b4-5), that is, to the shadows on the wall of the cave facing them. Onoma may also have the broader meaning of “word” as unit of language, as opposed to rhèma (derived from the verb erein, “to talk”) meaning “expression, phrase”, that is, a combination of words, as is for instance the case with the first definition of logos given by Socrates at, Theaetetus, 206d1-5, as “the [fact of] making clear one’s own dianoia (thought) through sound by means of verbal expressions (rhèmatôn) and words (onomatôn)” (see also Theaetetus, 168b8 et 184c1, where the two words are used together). In the Sophist on the other hand, the Elean Stranger uses these two words with specialized grammatical meanings, giving rhèma the meaning “verb”, with the following definitions: for rhèma, “the [one] being a revealer regarding actions (praxesin, dative plural of praxis)” and for onoma, “the vocal sign regarding those who act (prattousi, present participle masculine or neuter dative plural of prattein) in these [actions]” (Sophist, 262a1-7). What must be remembered here is that the grammatical language was almost nonexistent in the time of Plato, that for instance there was no words to distinguish between noun, adjective, pronoun and the like or to name the functions of words in a sentence (subject, attribute, predicative expression, complement and the like) and that even this distinction made by the stranger between nouns/names and verbs, that is, between “actors” and “actions”, was new, which explains why he had to define the specialized meaning he was giving to onoma and rhèma, which was not their usual meaning at the time. If this gross distinction between only these two classes of words, “names/nouns” and “verbs” is enough for him, it is because what he wants us to understand is that for a logos, that is, for a combination of words intended to have meaning, indeed to be meaningful, it must combine these two categories of words. As he himself says, neither a list of names/nouns without a verb, or of verbs without a name/noun has meaning. For a combination of words to have meaning, it must refer, or pretend to refer, to a “fact (pragma)” associating one or more “actors” (referred to by onomata) with one or more “actions (praxeis)” depicted by “verbs” (rhèmata), making it possible to establish a relationship between the words uttered and observable “facts”, the meaning of the logos thus uttered depending on the adequacy of the words used with what they purport to describe.
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Ousia (noun): the usual meaning of this word in the time of Socrates and Plato was “that which is one's own, one's substance, property (especially real estate)”. But this word is derived from ousa, the present participle feminine of einai (“to be”), with a derivation similar to that leading in English from “being” to “beingness” (the neologism I use to translate ousia). Already, in Latin, Cicero had done the same thing to translate ousia which he was reading in Plato’s dialogues, coining the neologism essentia (from esse, “to be” in Latin), which has been transcribed into English as “essence”, a word sometimes used to translate ousia. The problem with these translations, in Latin as essentia as well as in English as “essence” or “beingness” it that they don’t import the usual meaning of ousia in Greek, which is fundamental for Plato and must always be present in the back of the mind, even when ousia seems to have in the dialogues a “technical” and “metaphysical” meaning. Indeed, the word, derived from a root referring to “being” (what one is), had taken a meaning referring to “having” (what one has, what one owns), suggesting that we are what we own from a material standpoint. And it is precisely this way of thinking that Plato wants to challenge without changing vocabulary, but merely reverting to the root of the word. What makes the true “wealth”, that is, the true “good”, of human beings? Is it real estate and material wealth or something else? This idea of “value”, this reference to what is “good” in the most general sense not limited to material good, must always be kept in mind when reading this word in Plato’s dialogues. But most translations of ousia in English force on the reader a choice between the “material” understanding in the sphere of “having” (the usual meaning, translated by words such as “property” or “wealth”) and the “metaphysical” meaning in the sphere of “being” (“technical meaning”, usually translated as “essence” or simply “being”). This is odd since English, unlike French, has a word which has both meanings, the word “substance”, for which the Merriam-Webster Dictionary lists, among other, both the meaning of “essence” and that of “property” and the American Heritage Dictionary the meaning of “essence” and that of “material possessions; goods; wealth”. But it is probably precisely because “substance” keeps the dual meaning of ousia (plus others, not relevant here) that translators, who do not realize that Plato plays with these two meanings, avoid the word to show they have understood in each case whether he uses it (exclusively in their mind) in one or the other sense!
Now, to make things still trickier, this “technical” meaning in the sphere of being is grounded in a “grammatical” sense stemming from its etymology, that of “predicative expression”, that is, the a of a sentence having the form x esti a (“x is a”) saying something, whatever it might be, that the subject x of the sentence, the “being (to on)”, “is (esti)”, that is, “the what it is (to ti esti)”, which explains the fact that, in Aristotle’s works, ousia and to ti esti are  synonymous. It is that same Aristotle who, with his categories, restricted the scope of ousia/to ti esti to only a subset of all the predicates of the subject, those which are permanent and properly apply to it at all times, in opposition to other predicates which he precisely tries to “categorize”: “accident” (something which the subject ‘is” only temporarily and “accidentally” and that other subjects, of the same species or of another species, might as well be), “quantity”, “position”, and so on. For Plato, this categorization is secondary compared to the main issue, which is to identify the relation with the “good” of all the predicates relevant regarding the subject, whether temporary or permanent. The question which matters for him is not what the subject is (ousia as “being”), but what is good for that subject (ousia as “value”). Hence the importance for him of the dual meaning of the word ousia and its import of the idea of “value”, which explains why he prefers this word to the expression to ti esti, which eliminates this import.
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Paschein (verb; aorist pathein): the general meaning of this verb is “to have something done to one, suffer, be affected”, as opposed to prattein, “to act, achieve, accomplish” and also “be busy with, do business” in a subjective perspective, or poiein, “make, produce, do”, in an objective perspective. It implies an idea of passivity in opposition with the idea of activity implied by prattein or poiein.
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Pathèma (noun; pl. pathèmata): substantive derived from paschein through the aorist pathein, by the same derivation leading to pragma from prattein (and poièma from poiein). These substantives may be compared to another series of substantives: pathos derived from paschein, praxis derived from prattein and poièsis derived from poiein. The words of the first series (pathèma, pragma, poièma) are more concrete than those of the second series (pathos, praxis, poièsis) and in general refer to a specific occurrence of what the verb implies (a specific instance of “affection”, something specific that someone or something “suffers”, for pathèma; a specific instance of “action”, a specific “affair” or “business”, for pragma; a specific production or achievement, and, in a more specialized sense, a specific literary work, for poièma, at the root of the English word “poem”), while the words of the second series refer to what the verb implies in the abstract, with no reference to a specific instance (the fact of suffering in general, or an unspecified instance of suffering or affection only to the extent that it is an occurrence of the fact of suffering, for pathos; an unspecified “act” or “activity”, or merely the fact of acting, for praxis; the fact of producing something, with no reference to a specific production, or, in a specialized sense, a literary work as such with no specific work in mind, for poièsis).
The pair pathèma (“affection” in the sense of “what affects us”, positively or negatively, physically or morally) – pragma is important in Plato’s writings since he uses the word pathèma to refer globally to what he associates with each of the four segments of the line in the analogy of the line at the end of book VI of the Republic, and the word pragma in several dialogues to refer to what words, the constituent parts of logos, are supposed to refer to. Indeed, it is important to always keep in mind the relation of complementarity which exists between these two words each time either one is used by Plato. This is the reason why the usual translation of pragma as “thing” is misleading, since it erases the idea of something active, at least on our senses and/or our mind. Through the use of pathèma in the analogy of the line, both in the visible realm and in the intelligible realm, Plato wants to suggest that the whole of our mental activity, whether directly induced by sensations or not, is the result of the “action” of something outside our mind, a pragma, which is not necessarily sensible, material, visible, tangible, but which must be there to explain the phenomenon of thought about it. When the stranger form Elea, in the Sophist, defines the “verb” (rhèma) as “the [one] being a revealer regarding actions (praxesin, dative plural of praxis)” and the “name/noun” (onoma) as “the vocal sign regarding those who act (prattousi, present participle masculine or neuter dative plural of prattein) in these [actions]” (Sophist, 262a1-7) and adds a few lines later that a logos (“speech”) is necessarily a speech on something (tinos einai logon, 262e6) and must “associat[e] a pragma to a praxis by means of a name/noun and a verb” (262e13-14), he means that a logos has meaning only by reference to a pragma, that is, to something “acting”, “activating” our mind (though the senses or not), constituting a specific instance of a praxis (in the broadest possible sense, including passive attitudes on the part of the subject, as can be seen from his first example, “Theaetetus sits” (263a2)) depicted by a specific verb (rhèma) implying a specific subject (acting or being affected), described by a noun/name. And if, in the activity described by the logos, the subject may be acting or affected, the pragma depicted by the logos, which should not be limited to the “subject”, to the “thing”, but considered as including the whole of the “activity” described by the logos, is always acting on the mind of the person producing the logos, which justifies the use of the word pragma about it, and of pathèma about what this pragma produces in the mind of that person.
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Phantasma (noun; pl. phantasmata): substantive derived from the verb phantazesthai (“to become visible, appear”), itself derived from phainesthai (“display, bring to light, make known”, and also, intransitive, “come to light, appear”), meaning “apparition, phantom, vision”. It is one of the words used by Socrates in the analogy of the line and the allegory of the cave to refer to “reflections” (Republic VI, 510a1; VII, 516b5), which he gives as an example, along with shadows, of what he means by eikones (“images, similitudes”), being careful in each case to add “in bodies of water” to make clear that what he has in mind is indeed “reflections”, which allows him to vary his vocabulary and to use also the word eidolon (“image, likeness, phantom”, Republic VII, 516a7), here again adding “in bodies of water”, thus showing that it is not the word which is important and that it is quite possible to understand one another using different words to talk about the same thing.
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Philos (adjective): “beloved, dear, friend” with regard to both persons and things, which leads to the prefix philo- found in a great many words, the second part of the word specifying what one is philos of. Thus for instance philosophos (“friend of wisdom”), philanthrôpos (“friend of human beings”). The feeling toward what one is philos of is philia, which differs from erôs by the absence of sexual overtones, even if philia may also be translated as “love” and erôs refer to a kind of love not necessarily physical and devoid of sexual connotation.
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Philosophos (noun): this word has been transcribed into English as “philosopher”, but this mere import may be misleading if the word is understood based on what is nowadays a “philosopher”. Yet, this ambiguity is nothing new and was already known by Plato, even if those his contemporaries used to call “philosophers” didn’t necessarily look like today’s philosophers, the only thing they have in common being to have little to do with what Plato called by this name. Most of book VI of the Republic; after Socrates has stated his proposal that philosophoi should rule (Republic V, 473c11-d6), is dedicated to making clearer what he means by this word and to point at the difference between his understanding of philosophos and that of most people. And the portrait of the “philosopher” he draws at the center of the Theaetetus, far from being the portrait of the philosophos dear to the heart of Plato is in fact a caricature of the philosopher as the geometer Theodorus imagines it (the word philosophos is used only once  toward the end of the portrait, at 175e1, in the expression “the one you call philosophos” addressed by Socrates to Theodorus), that is the “philosopher” as seen by a “scientist”, who is but an eternal daydreamer withdrawing from the real world, in complete opposition with the philosophos according to Plato, worthy of leading his fellow human beings and for whom it is a requirement to do so.
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Phusis (noun; pl. phusei): substantive derived from the verb phuein, “bring forth, beget, produce”, and also passive “to be born, grow”. According to Benveniste, phusis means “realization (completed) of a becoming (accomplissement (effectué) d’un devenir)”, “nature as realized with all its properties (nature en tant qu’elle est réalisée avec toutes ses propriétés)”. The word has many meanings such as “origin”, “birth”, “growth”, “nature”, all involving the idea of growth and the various stages of this process or of what produces it. Phusis is sometimes opposed to nomos (“law”) as that which is “by nature (phusei)” to what is the result of human conventions.
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Pistis (noun): “trust (in others)”, “confidence”, “trustworthiness”, “faith”, and also “assurance, guarantee”. It is the name Socrates gives, in the analogy of the line at the end of book VI of the Republic, to the pathèma (see this word) he associates with the second segment of the visible, the one where, having understood that sight doesn’t reveal things (pragmata) as they are, but gives us only visual “images” revealing only their outer appearance, we are no longer in the illusion (eikasia) of believing that things are such as we see them, but have confidence that these images provided by sight are in most case good enough for us to act in this material and visible world and find our way through what is around us, which doesn’t exempt us, quite the contrary, from the task of trying to grasp their principles of intelligibility and their relations with the good, in the intelligible realm.
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Polis (noun; plural poleis): “city”: refers both to a geographic entity and to a community living in such a place. A Greek polis in the time of Plato was not limited to the built-up area of an urban agglomeration but included rural areas around it belonging to the citizens of that polis and providing it with at least part of what it needed, especially in terms of food. As an example, the polis of Athens included most of Attica all the way to Cape Sounion. When Plato talks about polis, the word should not be understood in the modern sense of “city” or “town”, but rather in a sense closer to that of “state”, of a political (a word derived from polis) community constituting an administrative unity with regard to neighboring “cities”, with its own government, its own constitution and laws, its army, and so on.
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Politès (noun; pl. politai): inhabitant of the polis, that is, “citizen”. But not all the inhabitants were politai, only, in Athens for instance, the free legitimate males natives from the city aged at least twenty and whose father was already a citizen. Excluded from this status were women and children, slaves and resident aliens, called “metics” (metoikoi, that is etymologically “those who have their house (oikos) amongst (meta) us”), most often originating from another Greek city, and thus speaking the same language as the citizens. Thus, for instance, Cephalus, the father of Lysias and Polemarchus (all of them historical characters), resident in Piraeus, the main harbor of Athens, in whose house the dialogue reported in the Republic takes place, was a “metic” native from Syracuse in Sicily, another Greek city at the time, though located in Sicily.
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Politeia (noun): this word derived from politès has a multiplicity of meaning, some of them relative to individuals as politai, others relative to the community, the polis as a whole: it may simply mean “citizenship”, that is, the mere fact for someone to be a politès of one or another city; it may also refer to the body of rights and duties of a politès; or else, the lifestyle fitting for a politès; but it may also refer to the gathering of all the politai; or to the organization of the polis describing the various roles expected from its politai, that is, the “constitution” organizing the life of the city and its politai, giving to “constitution” a broader sense that that of the word nowadays, including the whole body of laws of the city; and, eventually, but only lately and probably not before Aristotle, thus not in the time of Plato, it came to designate a specific type of government of the politai corresponding to what is now called “republic”. Politeia is the Greek title of the dialogue ill-advisedly called in English Republic, and it is not mere chance if Plato chose this title for a dialogue focusing on what makes a good life for human beings, animals bound by nature to live in society, that is, “political” animals, for whom it is impossible to dissociate the individual from the collective since the laws of the city are made by human beings, but human beings are raised and educated by the city, its laws and system of values. It is this intrication implied by the plurality of senses of politeia which is lost in the translation by Republic. “Citizenship” would have been a better translation of this title.
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Politikos (adjective): “of, for, or relating to a city and its citizens”. It is the word at the root of the English words “politic”, “politics”, “political” and “politician”. In Greek, the word could be used as a noun, with an article, to mean “politician”, which is what Plato does. The Sophist starts with a question of Socrates to the stranger from Elea which Theodorus brought along with him, asking him if, for his fellow citizens (the citizens of Elea, in Italy), the words sophistès, philosophos and politikos refer to the same person or to different persons. The Sophist deals with the difference between sophistès and philosophos and is followed by the Statesman, sometimes also called Politicus (Politikos in Greek), which deals with the politikos. The question of Socrates points both at the issue of the confusion between sophists and philosophers (which was responsible for the death of Socrates, taken for a sophist by most of his fellow Athenians in a time where sophists were not well-considered by most people) and at the influence of sophists on politicians of the time, whom they trained, against huge fees, to the art of public speech and the manner of being convincing with little or no care for truth, challenging religion and ancestral traditions by the teaching of materialist and relativist atheism. It also points at the proposal of Socrates in the Republic that philosophoi should rule, that is, become politikoi.
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Pragma (noun; pl. pragmata): pragma is to the verb prattein (“to act, achieve, accomplish”) what pathèma is to the verb paschein (see this word). On this word and his relationship with pathèma, and the limits of its usual translation as “thing”, see the entry on pathèma.
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Prattein (verb): “to act, achieve, accomplish”, in opposition to paschein, “to have something done to one, suffer, be affected”.
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Psuchè (noun; pl. psuchai): a word usually translated as “soul”, which is at the root of the English prefix “psycho-” found in such words as “psychology” or “psychiatry”. For Plato, the psuchè is primarily principle of life and movement. It is what “animates” the body (“animate” is derived from the Latin word anima, which is the Latin equivalent of the Greek psuchè). It is in a way everything which, in a human being (and more generally in any animal capable of moving by itself), is not material but is nonetheless needed to understand and explain that being. By definition, this immaterial part which is necessary to explain the experience we have of human beings, and which we somehow experience within ourselves as far as we are concerned, eludes “scientific” understanding and certainty regarding both its nature and its destiny, especially at death, even though it is what constitutes most properly the anthrôpos, which cannot be searched in the aggregate of matter constantly changing and always renewed by food that the perishable body is. Anthrôpoi cannot know for sure in this life what happens at death. The Phaedo doesn’t attempt to “demonstrate” the immortality of the psuchè, which is impossible for human reason. Indeed, if Plato’s Socrates had such a demonstration, absolutely convincing for all, he wouldn’t need to propose several of them, as he does in this dialogue. All he does is to assume the immortality of the psuchè as an hypothesis and then search all the arguments, none of which is binding, giving plausibility to this hypothesis, and put to the test its consistency with other data from experience and other more abstract reasoning, to end up on the avowal, minutes before drinking the hemlock, that, as far as he is concerned, he has taken the “beautiful risk” (Phaedo, 114d6) of building his life on this assumption and on the complementary one that the good for a human being is the good for one’s psuchè, even at a time where it implied for him to accept an unjust death because it was decided by his fellow citizens in respect of the laws in effect. In book IV of the Republic, Socrates conducts an analysis of the soul which, in order to explain the inner conflicts taking place inside man, distinguishes three parts in the soul, which he respectively describes as logistikon (“reasonable”) to designate reason as the unifying principle, epithumètikon (“desiring”), the one, plural, subjected to eipthumiai (“desires, passions, yearnings, appetites”), and thumoeides(“having to do with thumos (see this word)”, “susceptible”, in between the two others. In the Phaedrus, he illustrates this tripartition through a myth picturing the soul as a chariot (representing the body) endowed with wings (because having through logos, reason, the power to rise toward the divine) pulled by two horses, one black, stubborn and hard to manage, picturing the epithumètikon (“desiring”) part of the soul, the other, white, easier to manage but capable of being led astray by the black horse, picturing the thumoeides (“susceptible”) part of the soul, driven by a charioteer who can only move the chariot through the two horses, which he must thus control and make to move together in the same direction.
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Rhèma (noun): a word derived from the verb eirein meaning “to talk”, which, in its usual sense, refers to any vocal expression made up of words. On the relation between this word and the word onoma (“name, word”) and the more specialized meaning (for rhèma, “verb” in the grammatical sense) that the stranger from Elea gives them in the Sophist, see the entry about onoma.
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Schèma (noun): word whose original meaning is close to that of eidos and idea (“external appearance”), meaning “form, shape, figure, air, manner, bearing”, which took a more technical meaning specializing to refer to geometrical “figures”. Contrary to eidos and idea which stem from a root meaning “to see”, schema derives from the verb echein, through the aorist schein, meaning “to have” and implying a relation of possession (echein meaning “to possess, hold, retain”). From this standpoint, it is the Greek equivalent of the Latin habitus (root of the English word “habit”), derived from the verb habere, Latin equivalent of echein. When, in the Meno, Socrates wants to help Meno understand what he means when he talks of a unique eidos common to all the aretai (“perfections, virtues”) which justifies that the same word be used to talk about all of them, in an attempt to have him explain in a synthetic manner what he means by aretè when he asks him whether human aretè can be taught, and Meno asks him an example of such a definition, it is not mere chance if the example he uses is precisely schèma, taken in its geometrical sense of “figure”: indeed, the geometrical figure may be considered the “embryo”, the most simplistic version, of eidos taken in a more general sense applying both the visible things and to abstract concepts.
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Sophos (adjective): “skilled in any handicraft or art”, or else “learned”, “clever, ingenious”, “wise”. The quality of the one being sophos is sophia, which goes from “skill” in any practical matter to “learning” and eventually “wisdom”. For Plato, this wisdom, which requires exhaustive knowledge, is out of reach of human beings in this life due to the inherent limitations of their nature and of logos, which is the tool with which they seek it. This is the reason why human beings can at best be philosophoi, that is, “in love with wisdom/knowledge”, trying to approach it as close as possible for human nature and each one’s specific nature. And the first step toward this wisdom is to admit that it is out of reach but that this is no reason to despair of logos and fall into misology (misologia, “hate of logos”, see, Phaedo, 89d4), which would be the worst kind of misanthropy, since logos is what distinguishes human beings from all other animals. If logos is not all-powerful, if it cannot give us access to undoubtable and demonstrable knowledge on the most important questions regarding the way of leading a good life as human beings (which justifies the “I know nothing” of Socrates), it still is the best tool at our disposal for that purpose and, in the same way it is not because sight doesn’t show us things as they are that we should refuse to trust it (pistis, see that word) and close our eyes forever, in the same way, it is not because our nous (“mind”) and the logos it makes possible don’t allow us to find undoubtable answers to the questions we ask ourselves that we should refuse altogether to use it and become alogoi (“irrational, deprived of reason”).
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Sophistès (noun): a word derived from the root sophos originally referring to any person who is master, expert in one’s craft, whichever it is. In the time of Socrates and Plato it had come to refer to teachers of oratory who were going from city to city asking huge sums of money for their services at forming the sons of the wealthiest families in view of a political career. In view of the results and in the political context of the time, the word thus took a pejorative connotation, which endures in the English words “sophist”, “sophism” or “sophistry”. The Sophists that are best known to us are those Plato staged in his dialogues, Protagoras, Hippias, Gorgias (each giving his name to a dialogue, even two in the case of Hippias), or else Prodicus (staged in the Protagoras, and mentioned in several other dialogues) and Thrasymachus (staged in the Republic).
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Sôphrosunè (noun): a word derived from sôs, meaning “safe and sound, alive and well”, and phrèn, which refer to the heart as seat of the passions or the mind, as seat of the mental faculties, perception and thought, through sôphrôn, meaning etymologically “having a sound mind”, and thus “wise”, but also more specifically “having control over the sensual desires, temperate, self-controlled”. Sôphrosunè is the quality of who is sôphrôn, “temperance”, “moderation”, and eventually a form of wisdom, in a sense close to that of sophia. Sophrôsunè, rather than sophia, is the theme of the Charmides because the dialogue stages teenagers and sôphrosunè, having a broader meaning than sophia, is a quality which may be expected from teenagers, more than sophia, which is seen more as the result of a long progression, thus, to be expected more, if not of old people, at least of mature adults. But when the dialogue ends up in a discussion between Socrates and Critias, sophia is indeed in the background, even if the word is seldom used.
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Technè (noun): “skill”, “technique” (the English word derived from it) as a set of rules, system or method of making or doing, especially in manual activities, “art, craft”. The word is sometimes opposed to epistèmè, which rather refers to a more theoretical and intellectual knowledge. But this doesn’t prevent Plato from talking of hè peri tous logous technè (“the art of speeches”, see for instance Phaedo, 90b7), or of rhètorikè technè (“rhetoric art”, for instance at, Phaedrus, 263b6), and not always in a pejorative way to downgrade rhetoric to a mere “cookery” since, when he describes to Phaedrus what a rhetoric worthy of that name should be according to him, namely, a “leading of the soul (psuchagogia)”, at, Phaedrus, 261a7-8, he keeps calling it a technè. At, Phaedrus, 276e5-6, he even goes so far as to refer to a dialektikè technè (“dialectic art, art of dialogue”), even if, at Sophist, 253d2-3, the stranger form Elea talks of a dialektikè epistèmè (rather than technè). We might say that epistèmè (“knowledge”) is the result to which technè (“art”) should lead.
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Telos (noun): “end” in the sense of “accomplishment, achievement”. For Plato, rather than turning back toward the origin and the past, which we cannot change, we must determine the telos toward which we must progress and which will make us anthrôpoi as excellent and happy as possible and derive from this the path which may lead us there.
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Thumos (noun): Originally, this word has a meaning close to that of psuchè and refers to the “heart” or the “soul” as seat of life; from there its meaning evolves toward that of “courage” and as referring to the seat of feelings, especially anger. In his analysis of the tripartite soul in book IV of the Republic (Republic IV, 436a8-441c3), Plato uses this word to refer to the intermediary part, which he also calls thumoeides, that is, “of the kind (eidos) of the thumos”. In the image of the soul as a winged chariot in the Phaedrus (Phaedrus, 246a7-b4 and 253c7-e5), thumos is pictured by the white horse. It is, along with desires (epithumiai, a word in which the root thumos is present along with the prefix epi-, “upon”, which means etymologically “what comes upon thumos to take control over it”), one of the two principles capable of moving (the two horses) the body (the chariot), which reason (the charioteer), unable to move the body by itself, must manage to master and tame to allow the chariot to move properly and go in the appropriate direction, which reason alone can determine. Desires (epithumiai, grouped in the part of the soul Plato names epithumètikon, that is, “desiring”) stem from corporeal needs (hunger, thirst, sexual appetite, and the like) while thumos is the part reacting to solicitations from the symbolic register expressed by words, that is, through logos, even if it remains alogon (deprived of reason) and reacts impulsively, instinctively, without taking the time to give much thoughts to its course of action: it involves the feeling of pride and honor, self-esteem, aggressiveness, and the like, feelings which answer no vital bodily needs.
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Trapeza (noun): “table”. For the role of this word in Plato’s dialogues, see the entry on klinè.
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Zèn (verb): “to live”, mostly about animals (including human beings).
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Zôion (noun): “living being”, mostly “animal”, as opposed to phuton (“plant”) (see for instance Republic VII, 532a9, where Socrates, recalling the allegory of the cave, describes what the freed prisoner who just exited the cave still has a hard time to see as ta zôia te kai phuta (“animals and plants”), while in the allegory he had just mentioned “human beings (anthrôpoi) and the rest”). This way of classifying opposes implicitly the idea of phuein (“to grow”) to that of zèn (“to live”), which implies the ability to move by oneself, not that animals don’t grow, but what distinguishes them from plants is their ability to be self-moving due to their having a psuchè (“soul” as principle of movement), which plants don’t have.
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Plato and his dialogues : Home - Biography - Works and links to them - History of interpretation - New hypotheses - Map of dialogues : table version or non tabular version. Tools : Index of persons and locations - Detailed and synoptic chronologies - Maps of Ancient Greek World. Site information : About the author.

First published April 25, 2021 - Last updated May 8, 2021
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