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.
Nor need it cause surprise that things disagreeable to the good man should seem pleasant to some men; for mankind is liable to many corruptions and diseases, and the things in question are not really pleasant, but only pleasant to these particular persons, who are in a condition to think them so.
Demonstration is also something necessary, because a demonstration cannot go otherwise than it does, ... And the cause of this lies with the primary premises/principles.
Even the best of men in authority are liable to be corrupted by passion. We may conclude then that the law is reason without passion, and it is therefore preferable to any individual.
If what was said in the Ethics is true, that the happy life is the life according to virtue lived without impediment, and that virtue is a mean, then the life which is in a mean, and in a mean attainable by every one, must be the best. And the same principles of virtue and vice are characteristic of cities and of constitutions; for the constitution is in a figure the life of the city.
So virtue is a purposive disposition, lying in a mean that is relative to us and determined by a rational principle, and by that which a prudent man would use to determine it. It is a mean between two kinds of vice, one of excess and the other of deficiency.
There is also a doubt as to what is to be the supreme power in the state: - Is it the multitude? Or the wealthy? Or the good? Or the one best man? Or a tyrant?
To leave the number of births unrestricted, as is done in most states, inevitably causes poverty among the citizens, and poverty produces crime and faction.
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.
It must not be supposed that happiness will demand many or great possessions; for self-sufficiency does not depend on excessive abundance, nor does moral conduct, and it is possible to perform noble deeds even without being ruler of land and sea: one can do virtuous acts with quite moderate resources. This may be clearly observed in experience: private citizens do not seem to be less but more given to doing virtuous actions than princes and potentates. It is sufficient then if moderate resources are forthcoming; for a life of virtuous activity will be essentially a happy life.
We maintain, and have said in the Ethics, if the arguments there adduced are of any value, that happiness is the realization and perfect exercise of virtue, and this not conditional, but absolute. And I used the term 'conditional' to express that which is indispensable, and 'absolute' to express that which is good in itself.