Ignorance more frequently begets confidence than does knowlege: it is those who know little, and not those who know much, who so positively assert that this or that problem will never be solved by science.

The fact of evolution is the backbone of biology, and biology is thus in the peculiar position of being a science founded on an improved theory, is it then a science or faith?

A scientific man ought to have no wishes, no affections, — a mere heart of stone.

We can allow satellites, planets, suns, universe, nay whole systems of universes, to be governed by laws, but the smallest insect, we wish to be created at once by special act.

An American Monkey after getting drunk on Brandy would never touch it again, and thus is much wiser than most men.

It is not the strongest of the species that survive, nor the most intelligent, but the one most responsive to change.

We must, however, acknowledge as it seems to me, that a man with all his noble qualities…still bears in his bodily frame the indelible stamp of his lowly origin.