Not to have known - as most men have not - either the mountain or the desert is not to have known one's self. Not to have known one's self is to have known no one.

Whenever man forgets that man is an animal, the result is always to make him less humane.

Custom has furnished the only basis which ethics have ever had.

A book ... unlike a television program, moving picture or any other 'modern means of communication' ... can wait for years, yet be available at any moment when it happens to be needed.

Any euphemism ceases to be euphemistic after a time and the true meaning begins to show through. It's a losing game, but we keep on trying.

To those who study her, Nature reveals herself as extraordinarily fertile and ingenious in devising means, but she has no ends which the human mind has been able to discover or comprehend.

Metaphysics may be, after all, only the art of being sure of something that is not so and logic only the art of going wrong with confidence.