The result, then, is that more plentiful and better-quality goods are more easily produced if each person does one thing for which he is naturally suited, does it at the right time, and is released from having to do any of the others.
In Book II, Socrates introduces the principle of specialization. According to Plato, political justice boils down to this guiding rule—that everyone do that to which their nature best suits them, and not meddle in any other business. Producers must produce according to their natures (e.g., the farmer farms, the carpenter builds wooden objects, the artist paints, and the doctor heals); warriors must fight; and the philosophers must rule.
What about someone who believes in beautiful things but doesn’t believe in the beautiful itself and isn’t able to follow anyone who could lead him to the knowledge of it? Don’t you think he is living in a dream rather than a wakened state? Isn’t this dreaming: whether asleep or awake, to think that a likeness is not a likeness but rather the thing itself that it is like?
In Book V, Socrates explains what distinguishes the lover of sights and sounds, the pseudo-intellectual, from the true philosopher. The lover of sights and sounds takes the sensible objects around him for the most real things, not recognizing that there is a higher level of reality in the intelligible realm. In particular, he goes around talking about beauty, billing himself as an expert on beauty, and yet he does not even realize that there is such a thing as the Form of the Beautiful, which is the cause of all sensible beauty.
They don’t understand that a true captain must pay attention to the seasons of the year, the sky, the stars, the winds, and all that pertains to his craft, if he’s really to be the ruler of a ship. And they don’t believe that there is any craft that would enable him to determine how he should steer the ship, whether the others want him to or not, or any possibility of mastering this alleged craft or of practicing it at the same time as the craft of navigation. Don’t you think that the true captain will be called a real stargazer, a babbler, and a good-for-nothing by those who sail in ships governed in that way?
After Socrates presents his notion of a philosopher-king in Book VI, Adeimantus objects by pointing out that all real-life philosophers are either vicious or useless. Socrates responds by drawing an analogy to a ship governed by violent men, ignorant of navigation. His intention is to demonstrate that a good philosopher would necessarily be considered useless under current circumstances. True knowledge is not valued in modern Athens, nor even believed possible, and so anyone who tries to live their life by pursuing and praising real knowledge (as the true philosopher must do) will be thought a useless fool.
Once one has seen it, however, one must conclude that it is the cause of all that is correct and beautiful in anything, that it produces both light and its source in the visible realm, and that in the intelligible realm it controls and provides truth and understanding, so that anyone who is to act sensibly in private or public must see it.
Socrates describes the Form of the Good in Book VI, the ultimate object of knowledge. The Form of the Good is the source of all other Forms—the source of the entire intelligible realm, of intelligibility itself, and of our cognitive capacity to know. Though Socrates is not able to describe the Form of the Good explicitly, he attempts to give us a sense of it by comparing it to the sun. It is only when a man grasps the Form of the Good that he achieves the highest level of cognition, understanding. When a guardian takes this last step he is finally ready to become a philosopher-king.
Under the tyranny of erotic love he has permanently become while awake what he used to become occasionally while asleep.
In Book IX, Socrates presents a long and psychologically astute portrait of the tyrannical man. The tyrannical man is governed by lawless desires, the sort of desires that in normal people only emerge occasionally in dreams (desires for illicit sexual unions or heinous murders). Leading him down this nightmarish path, and egging him constantly on to greater excess, is the tyrannical man’s erotic lusts. Socrates deems erotic love the greatest tyrant of all, and regards it as a dangerous emotion, best avoided by good men.