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

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.

For every fresh stage in our lives we need a fresh education, and there is no stage for which so little educational preparation is made as that which follows the reproductive period.

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

Failing to find in women exactly the same kind of sexual emotions, as they find in themselves, men have concluded that there are none there at all.

On the threshold of the moral world we meet the idea of Freedom, 'one of the weightiest concepts man has ever formed,' once a dogma, in the course of time a hypothesis, now in the eyes of many a fiction, yet we cannot do without it, even although we may be firmly convinced that our acts are determined by laws that cannot be broken.

The relation of the individual person to the species he belongs to is the most intimate of all relations.