Glaucon

Glaucon (; ; c. 445 BC – 4th century BC), son of Ariston, was an ancient Athenian and Plato's older brother. He is primarily known as a major conversant with Socrates in the Republic. According to Debra Nails, two major facts about Glaucon's life can be ascertained from a single comment by Socrates in the Republic, that Glaucon was old enough to have distinguished himself in a battle at Megara, and that he was the eromenos of the poet and statesman Critias. In Book V of the Republic, an exchange between Socrates and Glaucon indicates that Glaucon owned property where he kept and bred sporting dogs and game birds.

He is also referenced briefly in the beginnings of two other dialogues of Plato, the Parmenides and Symposium. Glaucon also appears in Xenophon's Memorabilia, and is referenced in Aristotle's Poetics, where Aristotle states: "The true mode of interpretation is the precise opposite of what Glaucon mentions. Critics, he says, jump at certain groundless conclusions; they pass adverse judgement and then proceed to reason on it; and, assuming that the poet has said whatever they happen to think, find fault if a thing is inconsistent with their own fancy."