Purple in Plato’s Republic The achievement of the “good of the whole” is the purpose of Socrates’ constitution, proposed in Plato’s Republic. To explain this purpose to Adeimantus in Book IV of The Republic, Plato has Socrates invoke the analogy of the “purple eye,” (90) which is employed at the opening of the Book, after Adeimantus states that Socrates’ citizen-guardians would live in misery because they would always be “on guard,” as it were, and would never actually enjoy themselves.

Plato uses the theme of purple throughout the text, which has symbolic power (as it represents royalty and majesty) to craft the response of Socrates. The ideal is what Socrates has in mind—the highest reality—which is made plain in the Allegory of the Cave in Book VII of The Republic. It is from this cave that the ignorant must emerge, so that they might see reality for what it is, rather than the unreal spectacle of shadows playing upon the wall, which they take for reality. The highest reality—the ideal—must be reached through hard work (the climb up the mountain of philosophy towards truth). Plato believes in the philosopher-king, the ruler who understands the reality...

The ruler, clad in the royal color of purple, would lead his people in the same way that a good father would lead his children—not to excess or frivolity but to virtue and good habits that benefit the whole of the community. Life, in other words, should be ordered and inherently selfless rather than disordered and self-centered. Socrates’ purple analogy can be seen, in this sense, as a central point of Plato’s argument. The eye looks outward to others, and it is when one turns inward towards self-interest, the society begins to falter: Plato suggests, for example, that privatization is what destroys the city when he asks, “But when some suffer greatly, while others rejoice greatly, at the same things happening to the city or its people, doesn’t this privatization of pleasures and pains dissolve the city?”(136). What is good for the whole is what must always be maintained—and that depends on the guardians always being on guard.
The purple eye also relates to the concept of the truth-ideal and the need for philosophy to be the guiding force of any community because, as Socrates states, the eye is the most beautiful and “noblest” feature…