Every formed disposition of the soul realizes its full nature in relation to and dealing with that class of objects by which it is its nature to be corrupted or improved.
Prudence as well as Moral Virtue determines the complete performance of a man's proper function: Virtue ensures the rightness of the end we aim at, Prudence ensures the rightness of the means we adopt to gain that end.
Nature does nothing without a purpose. In children may be observed the traces and seeds of what will one day be settled psychological habits, though psychologically a child hardly differs for the time being from an animal.
There are, then, three states of mind ... two vices--that of excess, and that of defect; and one virtue--the mean; and all these are in a certain sense opposed to one another; for the extremes are not only opposed to the mean, but also to one another; and the mean is opposed to the extremes.
The male has more teeth than the female in mankind, and sheep and goats, and swine. This has not been observed in other animals. Those persons which have the greatest number of teeth are the longest lived; those which have them widely separated, smaller, and more scattered, are generally more short lived.
Happiness is something final and complete in itself, as being the aim and end of all practical activities whatever .... Happiness then we define as the active exercise of the mind in conformity with perfect goodness or virtue.
Also our fellow competitors, who are indeed the people just mentioned - we do not compete with men who lived a hundred centuries ago, or those yet not born, or the dead, or those who dwell near the Pillars of Hercules, or those whom, in our opinion or that of others, we take to be far below us or far above us. So too we compete with those who follow the same ends as ourselves; we compete with our rivals in sport or in love, and generally with those who are after the same things; and it is therefore these whom we are bound to envy beyond all others. Hence the saying.
Therefore the good man ought to be a lover of self, since he will then both benefit himself by acting nobly and aid his fellows; but the bad man ought not to be a lover of self, since he will follow his base passions, and so injure both himself and his neighbors. With the bad man therefore, what he does is not in accord with what he ought to do, but the good man does what he ought, since intelligence always chooses for itself that which is best, and the good man obeys his intelligence.