If thinking is like perceiving, it must be either a process in which the soul is acted upon by what is capable of being thought, or a process different from but analogous to that. The thinking part of the soul must therefore be, while impassable, capable of receiving the form of an object; that is, must be potentially identical in character with its object without being the object. Mind must be related to what is thinkable, as sense is to what is sensible.

Some men are just as sure of the truth of their opinions as are others of what they know.

Masculine republics give way to feminine democracies, and feminine democracies give way to tyranny.

Greatness of spirit is accompanied by simplicity and sincerity.

There is more both of beauty and of raison d'etre in the works of nature- than in those of art.

It is our choice of good or evil that determines our character, not our opinion about good or evil.

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.