I fully subscribe to the judgement of those writers who maintain that of all the differences between man and the lower animal, the moral sense of conscience is by far the most important....It is the most noble of all the attributes of man.

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.

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.

Multiply, vary, let the strongest live and the weakest die.

I cannot persuade myself that a beneficient and omnipotent God would have designedly created...that a cat should play with mice.

Sympathy for the lowest animals is one of the noblest virtues with which man is endowed.

I never gave up Christianity until I was forty years of age.