The virtue of a faculty is related to the special function which that faculty performs. Now there are three elements in the soul which control action and the attainment of truth: namely, Sensation, Intellect, and Desire. Of these, Sensation never originates action, as is shown by the fact that animals have sensation but are not capable of action.
Those who are not angry at the things they should be angry at are thought to be fools, and so are those who are not angry in the right way, at the right time, or with the right persons.
Since the whole city has one end, it is manifest that education should be one and the same for all, and that it should be public, and not private - not as at present, when every one looks after his own children separately, and gives them separate instruction of the sort which he thinks best; the training in things which are of common interest should be the same for all. Neither must we suppose that any one of the citizens belongs to himself, for they all belong to the state, and are each of them a part of the state, and the care of each part is inseparable from the care of the whole.
Thus it is thought that justice is equality; and so it is, but not for all persons, only for those that are equal. Inequality also is thought to be just; and so it is, but not for all, only for the unequal. We make bad mistakes if we neglect this for whom when we are deciding what is just. The reason is that we are making judgements about ourselves, and people are generally bad judges where their own interests are involved.
Just as a royal rule, if not a mere name, must exist by virtue of some great personal superiority in the king, so tyranny, which is the worst of governments, is necessarily the farthest removed from a well-constituted form; oligarchy is little better, for it is a long way from aristocracy, and democracy is the most tolerable of the three.
For the real difference between humans and other animals is that humans alone have perception of good and evil, just and unjust, etc. It is the sharing of a common view in these matters that makes a household and a state.
In a word, acts of any kind produce habits or characters of the same kind. Hence we ought to make sure that our acts are of a certain kind; for the resulting character varies as they vary. It makes no small difference, therefore, whether a man be trained in his youth up in this way or that, but a great difference, or rather all the difference.
Youth should be kept strangers to all that is bad, and especially to things which suggest vice or hate. When the five years have passed away, during the two following years they must look on at the pursuits which they are hereafter to learn. There are two periods of life with reference to which education has to be divided, from seven to the age of puberty, and onwards to the age of one and twenty.