Each organic being is striving to increase in a geometrical ratio . . . each at some period of its life, during some season of the year, during each generation or at intervals, has to struggle for life and to suffer great destruction . . . The vigorous, the healthy, and the happy survive and multiply.

In regard to the amount of difference between the races, we must make some allowance for our nice powers of discrimination gained by a long habit of observing ourselves.

Man with all his noble qualities, with sympathy which feels for the most debased, with benevolence which extends not only to other men but to the humblest living creature, with his god-like intellect which has penetrated into the movements and constitution of the solar system- with all these exalted powers- Man still bears in his bodily frame the indelible stamp of his lowly origin.

The age-old and noble thought of 'I will lay down my life to save another,' is nothing more than cowardice.

Light may be shed on man and his origins.

At no time am I a quick thinker or writer: whatever I have done in science has solely been by long pondering, patience and industry.

If man had not been his own classifier, he would never have thought of founding a separate order for his own reception.