Nature makes nothing incomplete, and nothing in vain.
Knowing what is right does not make a sagacious man.
The excellence of a thing is related to its proper function.
It is evident, then, that there is a sort of education in which parents should train their sons, not as being useful or necessary, but because it is liberal or noble.
... There must then be a principle of such a kind that its substance is activity.
A common danger unites even the bitterest enemies.