[Idea] of good, the source of truth, 6. [508] (cp. [505]); a cause like the sun, ib. [508]; 7. [516], [517]; must be apprehended by the lover of knowledge, 7. [534];
—ideas and phenomena, 5. [476]; 6. [507];
—ideas and hypotheses, 6. [510];
—absolute ideas, 5. [476] [cp. Phaedo 65, 74; Parm. 133]; origin of abstract ideas, 7. [523]; nature of, 10. [596]; singleness of, ib. [597] [cp. Tim. 28, 51].
Idea. [The Idea of Good is an abstraction, which, under that name at least, does not elsewhere occur in Plato’s writings. But it is probably not essentially different from another abstraction, ‘the true being of things,’ which is mentioned in many of his Dialogues [cp. passages cited s. v. [Being]]. He has nowhere given an explanation of his meaning, not because he was ‘regardless whether we understood him or not,’ but rather, perhaps, because he was himself unable to state in precise terms the ideal which floated before his mind. He belonged to an age in which men felt too strongly the first pleasure of metaphysical speculation to be able to estimate the true value of the ideas which they conceived (cp. his own picture of the effect of dialectic on the youthful mind, 7. [539]). To him, as to the Schoolmen of the Middle Ages, an abstraction seemed truer than a fact: he was impatient to shake off the shackles of sense and rise into the purer atmosphere of ideas. Yet in the allegory of the cave ([Book VII]), whose inhabitants must go up to the light of perfect knowledge but descend again into the obscurity of opinion, he has shown that he was not unaware of the necessity of finding a firm starting-point for these flights of metaphysical imagination (cp. 6. [510]). A passage in the Philebus (65 A) gives perhaps the best insight into his meaning: ‘If we are not able to hunt the good with one idea only, with three we may take our prey,—Beauty, Symmetry, Truth.’ The three were inseparable to the Greek mind, and no conception of perfection could be formed in which they did not unite. (Cp. Introduction, [pp. lxix], [xcvii]).]
Ideal state, is it possible? 5. [471], [473]; 6. [499]; 7. [540] (cp. 7. [520], and Laws 4. 711 E; 5. 739); how to be commenced, 6. [501]; 7. [540]:
—ideals, value of, 5. [472]. For the ideal state, see [City], [Constitution], [Education], [Guardians], [Rulers], etc.
Ignorance, nature of, 5. [477], [478]; an inanition (κένωσις) of the soul, 9. [585].
[Iliad], the style of, illustrated, 3. [392 E] foll.; mentioned, ib. [393 A]. Cp. [Homer], [Odyssey].
Ilion, see [Troy].
Illegitimate children, 5. [461 A].
Illusions of sight, 7. [523]; 10. [602] [cp. Phaedo 65 A; Phil. 380, 42 D; Theaet. 157 E].
Images, (i.e. reflections of visible objects), 6. [510]; 10. [596] (cp. Tim. 52 D). 357
[Imitation] in style, 3. [393], [394]; 10. [596] foll., [600] foll.; affects the character, 3. [395]; thrice removed from the truth, 10. [596], [597], [598], [602 B]; concerned with the weaker part of the soul, ib. [604].