Conscientious and careful physicians allocate causes of disease to natural laws, while the ablest scientists go back to medicine for their first principles.
In the human species at all events there is a great diversity of pleasures. The same things delight some men and annoy others, and things painful and disgusting to some are pleasant and attractive to others.
Happiness does not consist in amusement. In fact, it would be strange if our end were amusement, and if we were to labor and suffer hardships all our life long merely to amuse ourselves.... The happy life is regarded as a life in conformity with virtue. It is a life which involves effort and is not spent in amusement.
The business of every art is to bring something into existence, and the practice of an art involves the study of how to bring into existence something which is capable of having such an existence and has its efficient cause in the maker and not in itself.