Now, in furthering his concept of the Ideal State, Socrates divides the citizens into three groups: the Guardians are divided into two groups, the rulers and the auxiliaries; the rulers take priority in ruling the state, and the auxiliaries aid them. The third group is essentially the same as has been previously discussed, the craftsmen. As we might expect, the rulers are the very best of the Guardians; they must be older and more experienced men. These rulers must be incorruptible and impervious to bribes; in their youth and as they mature, they will have been tested to ensure their honesty. In other words, the rulers will rule as heads of state; the auxiliaries will police and defend the state; the craftsmen will conduct the necessary day-to-day business of the state.
At this point in the conversation, it occurs to Socrates that the three classes may at some point encroach upon one another and cause discord in the state. What if, for example, any member of a given class asks how he came to be so classified?
Socrates proposes that the citizens be told "just one royal lie," a "needful falsehood." This falsehood is to take the form of a story, the Myth of the Metals, a myth that Socrates discusses in the text. Glaucon is extremely doubtful about the efficacy of this "royal lie" and so is Socrates, but he is hopeful that the myth will ensure the citizens' loyalty to the community and to their respective classes.
Socrates concludes Book III with a few other stipulations having to do with the respective classes. All of these stipulations are intended to ensure the harmony of the state.
By this time, it is plain that Plato's plan for the ideal state has manifested itself, in theory, in a "class society," but, whereas before Socrates has been talking about a division of labor, he is now addressing himself to what we may call a division of power. Familiar as he was in his lifetime to "power grabs" and revolutions, Plato seems to want to forestall and, it is to be hoped, to prohibit such dissension in the state with the division into three classes and the "necessary lie."
As we have seen thus far, the conversation has presented us with a kind of philosophical mixture of practical statecraft, mythology and its uses, kindred aspects of the arts, and metaphysics. Despite our having agreed earlier that necessary lies may be used to damage an enemy or to placate a crazy friend in distress, we are made uncomfortable by the lie of the Myth of Metals.
We must remember that Plato's is a society in what we may term a kind of "metaphysical flux"; it is a society of a pagan people who, yet quasi-polytheistic in their theological beliefs, seem to be attempting to think their way through to a monotheistic belief. We must remember here that we are dealing with an ancient Greek culture; it is not Hebraic. These people have not received the "word" of God; they are strangers to both the Old Testament and the New Testament. In attempting the Myth of Metals, Plato is wishing, perhaps, to ascribe the birth of the children of the three classes to what we may call a prime mover, or a first cause, or the will of God. During Plato's time, his culture was experiencing not only a series of political revolutions; it was undergoing a metaphysical upheaval as well. These aspects of Plato's culture are still warmly debated by scholars of ancient Greece and of the ancient world generally.
In his pursuit of ideal justice and a workable concept of the Good Man, it is frequently said of Plato that he rationalized Jesus Christ into existence three hundred years before the birth of Jesus.