Man's destructive hand spares nothing that lives; he kills to feed himself, he kills to clothe himself, he kills to adorn himself, he kills to attack, he kills to defend himself, he kills to instruct himself, he kills to amuse himself, he kills for the sake of killing.

There is no philosophy without the art of ignoring objections.

What a miserable world!--trouble if we love, and trouble if we do not love.

The concept of number is the obvious distinction between the beast and man.

I don't know what a scoundrel is like, but I know what a respectable man is like, and it's enough to make one's flesh creep.

There is no easy method of learning difficult things. The method is to close the door, give out that you are not at home, and work.

Nothing is necessary except God, and nothing is less necessary than pain.