The indifference, callousness and contempt that so many people exhibit toward animals is evil first because it results in great suffering in animals, and second because it results in an incalculably great impoverishment of the human spirit.

Gravity is a response to geometry.

I know little about nature and hardly anything about men.

One should respect an honest person even if he expresses opinions differing from one's own.

Reading, after a certain age, diverts the mind too much from its creative pursuits. Any man who reads too much and uses his own brain too little falls into lazy habits of thinking.

Morality is of the highest importance - but for us, not for God.

Education is only a ladder to gather fruit from the tree of knowledge, not the fruit itself