I regard sex as the central problem of life. And now that the problem of religion has practically been settled, and that the problem of labor has at least been placed on a practical foundation, the question of sex—with the racial questions that rest on it—stands before the coming generations as the chief problem for solution. Sex lies at the root of life, and we can never learn to reverence life until we know how to understand sex.

The mathematician has reached the highest rung on the ladder of human thought.

A sublime faith in human imbecility has seldom led those who cherish it astray.

The world's greatest thinkers have often been amateurs; for high thinking is the outcome of fine and independent living, and for that a professional chair offers no special opportunities.

Civilized men arrived in the Pacific, armed with alcohol, syphilis, trousers, and the Bible.

To live remains an art which everyone must learn, and which no one can teach.

Jealousy, that dragon which slays love under the pretence of keeping it alive.