If a man of good natural disposition acquires Intelligence [as a whole], then he excels in conduct, and the disposition which previously only resembled Virtue, will now be Virtue in the true sense. Hence just as with the faculty of forming opinions [the calculative faculty] there are two qualities, Cleverness and Prudence, so also in the moral part of the soul there are two qualities, natural virtue and true Virtue; and true Virtue cannot exist without Prudence.
... the friendship of worthless people has a bad effect (because they take part, unstable as they are, in worthless pursuits, and actually become bad through each other's influence). But the friendship of the good is good, and increases in goodness because of their association. They seem even to become better men by exercising their friendship and improving each other; for the traits that they admire in each other get transferred to themselves.
It is clear that those constitutions which aim at the common good are right, as being in accord with absolute justice; while those which aim only at the good of the rulers are wrong.
Music directly imitates the passions or states of the soul...when one listens to music that imitates a certain passion, he becomes imbued withthe same passion; and if over a long time he habitually listens to music that rouses ignoble passions, his whole character will be shaped to an ignoble form.
Laws, when good, should be supreme; and that the magistrate or magistrates should regulate those matters only on which the laws are unable to speak with precision owing to the difficulty of any general principle embracing all particulars.
Happiness itself is sufficient excuse. Beautiful things are right and true; so beautiful actions are those pleasing to the gods. Wise men have an inward sense of what is beautiful, and the highest wisdom is to trust this intuition and be guided by it. The answer to the last appeal of what is right lies within a man's own breast. Trust thyself.
But the whole vital process of the earth takes place so gradually and in periods of time which are so immense compared with the length of our life, that these changes are not observed, and before their course can be recorded from beginning to end whole nations perish and are destroyed.
Every art and every inquiry, and similarly every action and pursuit, is thought to aim at some good; and for this reason the good has rightly been declared to be that at which all things aim.