With highly civilised nations continued progress depends in a subordinate degree on natural selection; for such nations do not supplant and exterminate one another as do savage tribes.

He who understands baboon would do more towards metaphysics than Locke.

A fair result can be obtained only by fully stating and balancing the facts and arguments on both sides of each question." Charles Darwin

I suppose you are two fathoms deep in mathematics, and if you are, then God help you. For so am I, only with this difference: I stick fast in the mud at the bottom, and there I shall remain.

...conscience looks backwards and judges past actions, inducing that kind of dissatisfaction, which if weak we call regret, and if severe remorse.

It is scarcely possible to doubt that the love of man has become instinctive in the dog.

Man in his arrogance thinks himself a great work, worthy the interposition of a great deity. More humble and I believe true to consider him created from animals.