Some of you have the power of command, and in the composition of these he has mingled gold, wherefore also they have the greatest honour; others he has made of silver, to be auxillaries; others again who are to be husbandmen and craftsmen he has composed of brass and iron; and the species will generally be preserved in the children.

But as all are of the same original stock, a golden parent will sometimes have a silver son, or a silver parent a golden son.

And God proclaims as a first principle to the rulers, and above all else, that there is nothing which should so anxiously guard, or of which they are to be such good guardians, as of the purity of the race.
They should observe what elements mingle in their off spring; for if the son of a golden or silver parent has an admixture of brass and iron, then nature orders a transposition of ranks, and the eye of the ruler must not be pitiful towards the child because he has to descend in the scale and become a husbandman or artisan, just as there may be sons of artisans who having an admixture of gold or silver in them are raised to honour, and become guardians or auxiliaries.

For an oracle says that when a man of brass or iron guards the State, it will be destroyed.

Such is the tale; is there any possibility of making our citizens believe in it?
Not in the present generation, he replied; there is no way of accomplishing this; but their sons may be made to believe in the tale, and their sons' sons, and posterity after them.
I see the difficulty, I replied; yet the fostering of such a belief will make them care more for the city and for one another.