In all things which have a plurality of parts, and which are not a total aggregate but a whole of some sort distinct from the parts, there is some cause.
Men become builders by building and lyreplayers by playing the lyre; so too we become just by doing just acts, temperate by doing temperate acts, brave by doing brave acts.
Plants, again, inasmuch as they are without locomotion, present no great variety in their heterogeneous pacts. For, when the functions are but few, few also are the organs required to effect them. ... Animals, however, that not only live but perceive, present a great multiformity of pacts, and this diversity is greater in some animals than in others, being most varied in those to whose share has fallen not mere life but life of high degree. Now such an animal is man.
Conscientious and careful physicians allocate causes of disease to natural laws, while the ablest scientists go back to medicine for their first principles.
They who have drunk beer, fall on their back, but there is a peculiarity in the effects of the drink made from barley, for they that get drunk on other intoxicating liquors fall on all parts of their body, they fall on the left side, on the right side, on their faces, and and on their backs. But it is only those who get drunk on beer that fall on their backs with their faces upward.
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
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.
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.
And it is characteristic of man that he alone has any sense of good and evil, of just and unjust, and the like, and the association of living beings who have this sense makes family and a state.
Now, the causes being four, it is the business of the student of nature to know about them all, and if he refers his problems back to all of them, he will assign the "why" in the way proper to his science-the matter, the form, the mover, that for the sake of which.
Money was established for exchange, but interest causes it to be reproduced by itself. Therefore this way of earning money is greatly in conflict with the natural law.