No one writes anything worth writing, unless he writes entirely for the sake of his subject.

The principle of contradiction establishes merely the agreement of concepts, but does not itself produce concepts.

There are, first of all, two kinds of authors: those who write for the subject's sake, and those who write for writing's sake.

To form a judgment intuitively is the privilege of few; authority and example lead the rest of the world. They see with the eyes of others, they hear with the ears of others. Therefore it is very easy to think as all the world now think; but to think as all the world will think thirty years hence is not in the power of every one.

Compassion for animals is intimately associated with goodness of character, and it may be confidently asserted that he who is cruel to animals cannot be a good man.

A man shows his character just in the way in which he deals with trifles, for then he is off his guard.

First the truth is ridiculed. Then it meets outrage. Then it is said to have been obvious all along.