What are the moral convictions most fondly held by barbarous and semi-barbarous people? They are the convictions that authority is the soundest basis of belief; that merit attaches to readiness to believe; that the doubting disposition is a bad one, and skepticism is a sin.

Science is organized common sense where many a beautiful theory was killed by an ugly fact.

That man, I think, has had a liberal education, who has been so trained in youth that his body is the ready servant of his will.

Mr. Darwin's hypothesis is not, so far as I am aware, inconsistent with any known biological fact; on the contrary, if admitted, the facts of Development, of Comparative Anatomy, of Geographical Distribution, and of Palaeontology, become connected together, and exhibit a meaning such as they never possessed before; and I, for one, am fully convinced that if not precisely true, that hypothesis is as near an approximation to the truth as, for example, the Copernican hypothesis was to the true theory of the planetary motions.

I'd rather have an ape for an ancestor than a bishop.

The man of science has learned to believe in justification, not by faith, but by verification.

If a man cannot do brain work without stimulants of any kind, he had better turn to hand work it is an indication on Nature's part that she did not mean him to be a head worker.