[the virtues] cannot exist without Prudence. A proof of this is that everyone, even at the present day, in defining Virtue, after saying what disposition it is [i.e. moral virtue] and specifying the things with which it is concerned, adds that it is a disposition determined by the right principle; and the right principle is the principle determined by Prudence.
The saying of Protagoras is like the views we have mentioned; he said that man is the measure of all things, meaning simply that that which seems to each man assuredly is. If this is so, it follows that the same thing both is and is not, and is bad and good, and that the contents of all other opposite statements are true, because often a particular thing appears beautiful to some and ugly to others, and that which appears to each man is the measure
That in the soul which is called mind (by mind I mean that whereby the soul thinks and judges) is, before it thinks, not actually any real thing. For this reason it cannot reasonably be regarded as blended with the body
Our virtues are voluntary (and in fact we are in a sense ourselves partly the cause of our moral dispositions, and it is our having a certain character that makes us set up an end of a certain kind), it follows that our vices are voluntary also; they are voluntary in the same manner as our virtues.
Anger is always concerned with individuals, ... whereas hatred is directed also against classes: we all hate any thief and any informer. Moreover, anger can be cured by time; but hatred cannot. The one aims at giving pain to its object, the other at doing him harm; the angry man wants his victim to feel; the hater does not mind whether they feel or not.
We praise a man who feels angry on the right grounds and against the right persons and also in the right manner at the right moment and for the right length of time.
In the case of some people, not even if we had the most accurate scientific knowledge, would it be easy to persuade them were we to address them through the medium of that knowledge; for a scientific discourse, it is the privilege of education to appreciate, and it is impossible that this should extend to the multitude.
... 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.
People do not naturally become morally excellent or practically wise. They become so, if at all, only as the result of lifelong personal and community effort.