Every great advance in natural knowledge has involved the absolute rejection of authority.

Teach a man to read and write, and you have put into his hands the great keys of the wisdom-box.

It ought not to be unpleasant to say that which one honestly believes or disbelieves. That it so constantly is painful to do so, is quite enough obstacle to the progress of mankind in that most valuable of all qualities, honesty of word or of deed.

The great tragedy of science - the slaying of a beautiful hypothesis by an ugly fact.

If a man cannot see a church, it is preposterous to take his opinion about its altar-piece or painted window.

Teach a child what is wise, that is morality. Teach him what is wise and beautiful, that is religion!

Regarded anatomically, the resemblances between the foot of Man and the foot of the Gorilla are far more striking and important than the differences... be the differences between the hand and foot of Man and those of the Gorilla what they may the differences between those of the Gorilla and those of the lower Apes are much greater.