Excellence or virtue is a settled disposition of the mind that determines our choice of actions and emotions and consists essentially in observing the mean relative to us ... a mean between two vices, that which depends on excess and that which depends on defect.
The virtues [moral excellence] therefore are engendered in us neither by nature nor yet in violation of nature; nature gives us the capacity to receive them, and this capacity is brought to maturity by habit.
Everything that depends on the action of nature is by nature as good as it can be, and similarly everything that depends on art or any rational cause, and especially if it depends on the best of all causes.
If the state cannot be entirely composed of good men, and yet each citizen is expected to do his own business well, and must therefore have virtue, still inasmuch as all the citizens cannot be alike, the virtue of the citizen and of the good man cannot coincide. All must have the virtue of the good citizen - thus, and thus only, can the state be perfect; but they will not have the virtue of a good man, unless we assume that in the good state all the citizens must be good.
If every tool, when ordered, or even of its own accord, could do the work that befits it... then there would be no need either of apprentices for the master workers or of slaves for the lords.
For knowing is spoken of in three ways: it may be either universal knowledge or knowledge proper to the matter in hand or actualising such knowledge; consequently three kinds of error also are possible.
Now the goodness that we have to consider is clearly human goodness, since the good or happiness which we set out to seek was human good and human happiness. But human goodness means in our view excellence of soul, not excellence of body.
Teenagers these days are out of control. They eat like pigs, they are disrespectful of adults, they interrupt and contradict their parents, and they terrorize their teachers.
The wise man does not expose himself needlessly to danger, since there are few things for which he cares sufficiently; but he is willing, in great crises, to give even his life - knowing that under certain conditions it is not worthwhile to live.