Allegory of the caveThe Allegory of the Cave, or Plato's Cave, is an allegory presented by the Greek philosopher Plato in his work Republic (514a–520a) to compare "the effect of education (παιδεία) and the lack of it on our nature". It is written as a dialogue between Plato's brother Glaucon and his mentor Socrates, narrated by the latter. The allegory is presented after the analogy of the sun (508b–509c) and the analogy of the divided line (509d–511e). In the allegory "The Cave", Plato describes a group of people who have lived chained to the wall of a cave all their lives, facing a blank wall.
Theory of formsThe theory of Forms, theory of Ideas, Platonic idealism, or Platonic realism is a metaphysical theory, attributed to the Classical Greek philosopher Plato, suggesting that the physical world is not as real or true as timeless, absolute, unchangeable ideas. Ideas according to this theory, conventionally capitalized and translated as "Ideas" or "Forms", are the non-physical essences of all things, of which objects and matter in the physical world are merely imitations.
Form of the Good"Form of the Good", or more literally "the idea of the good" (ἡ τοῦ ἀγαθοῦ ἰδέα), is a concept in the philosophy of Plato. The definition of the Good is a perfect, eternal, and changeless Form, existing outside space and time. It is a Platonic ideal. The first references that are seen in The Republic to the Form of the Good are within the conversation between Glaucon and Socrates (454 c–d).
Analogy of the sunThe analogy of the sun (or simile of the sun or metaphor of the sun) is found in the sixth book of The Republic (507b–509c), written by the Greek philosopher Plato as a dialogue between his brother Glaucon and Socrates, and narrated by the latter. Upon being urged by Glaucon to define goodness, a cautious Socrates professes himself incapable of doing so. Instead he draws an analogy and offers to talk about "the child of goodness" ("ἔκγονός τε τοῦ ἀγαθοῦ").
NousNous, or Greek νοῦς (UKnaʊs, USnuːs), sometimes equated to intellect or intelligence, is a concept from classical philosophy for the faculty of the human mind necessary for understanding what is true or real. Alternative English terms used in philosophy include "understanding" and "mind"; or sometimes "thought" or "reason" (in the sense of that which reasons, not the activity of reasoning). It is also often described as something equivalent to perception except that it works within the mind ("the mind's eye").
