The second great channel through which the impulse towards the control of procreation for the elevation of the race is entering into practical life is by the general adoption, by the educated—of methods for the prevention of conception except when conception is deliberately desired.

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

When love is suppressed hate takes its place.

The absence of flaw in beauty is itself a flaw.

It is here [in mathematics] that the artist has the fullest scope of his imagination.

There is held to be no surer test of civilization than the increase per head of the consumption of alcohol and tobacco. Yet alcohol and tobacco are recognizable poisons, so that their consumption has only to be carried far enough to destroy civilization altogether.

All civilization has from time to time become a thin crust over a volcano of revolution.