We physicists, on the other hand, must take for granted that the things that exist by nature are, either all or some of them, in motion—which is indeed made plain by induction.
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....
We shall learn the qualities of governments in the same way as we learn the qualities of individuals, since they are revealed in their deliberate acts of choice; and these are determined by the end that inspires them.
To feel these feelings at the right time, on the right occasion, towards the right people, for the right purpose and in the right manner, is to feel the best amount of them, which is the mean amount - and the best amount is of course the mark of virtue.