Plato's The Republic Books 6 through 10
In books 6 through 10 of Plato's Republic, we see many different discussions on the subject of justice, philosophy, and goodness. The philosopher Socrates has now defined what a philosopher is. His next task is to show that a philosopher is best qualified to be the ruler of a state. A good ruler must surely know what Justice and Goodness are, for he must administer Justice and always act for the good of the community. But a philosopher, as we have seen, has knowledge of the Forms, so from this point of view at least, he is best qualified to be a ruler. A good ruler must have a good character as well as a good mind; he must always be truthful, high-minded, and disciplined, and never mean, petty, or cowardly. A philosopher will satisfy these requirements too, Socrates argues. Since the philosopher loves truth, he will always be honest and forthright.
Socrates is being much too idealistic here. The idea that a philosopher should be the ruler of a state is just an idle dream. Politicians should be practical and experienced. However philosophers have wisdom and goodness. Next Socrates is asked, "What is Goodness?" Socrates tries to answer this question in the form of an analogy. The Analogy of the Sun, as this is called, can be represented in a diagram:
Sight Knowledge
The Sun G ...