""(576a).
On the other hand there is the tyrant who by some misfortune to the city has been able to become the ruler to that city. Then that tyrant, who is now not only a ruler over many, he is a ruler without protection since even his neighbors are out to get him. This makes him a real tyrant who is:.
"really a slave, compelled to engage in the worst kind of fawning, slavery, and pandering to the worst kind of people. He is so far from satisfying his desires in any way that ΒΌ he's in the greatest need of most things and is truly poor. And, if indeed his state is like that of the city he rules, then he is full of fear, convulsions, and pain's throughout his life.""(579e).
So not only does he have slaves and is a slave to others, he is also a slave to his own fears and worries that by far he must lead the worst life of all.
Now after figuring out what type of life a tyrant can be expected to live, we must decide on what grounds is the philosophers' life a better life than that of a tyrant. This question goes back to Book II where Glaucon posed a question for Socrates to solve. He asked Socrates to prove that a man who leads a just life, with none of the rewards that come with being just, would live a happier life than a man who lives an unjust life, with all the benefits of being just, and none of the disadvantages of being unjust. This breaks down to a question of, is a philosophers life (just) better than a tyrants life (unjust). Socrates answers this question by setting up three arguments that are supposed to prove his claim that a philosophers life is the best life.
The first argument he sets up is the ranking of the five types of people. He ranks them in: "virtue and vice, in happiness and its opposite, in their order of their appearance.""(580b) He basically sets them up in the order their character puts them. As I wrote earlier the tyrant who's character who leads himself to be the most unjust and most wretched person of them all falls into last place in the ranking.
