Charm is a woman's strength just as strength is a man's charm.

If men and women are to understand each other, to enter into each other's nature with mutual sympathy, and to become capable of genuine comradeship, the foundation must be laid in youth.

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.

Thinking in its lower grades, is comparable to paper money, and in its higher forms it is a kind of poetry.

At the present day the crude theory of the sexual impulse held on one side, and the ignorant rejection of theory altogether on the other side, are beginning to be seen as both alike unjustified.

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

The conflict of forces and the struggle of opposing wills are of the essence of our universe and alone hold it together.