For every man the world is as fresh as it was at the first day, and as full of untold novelties for him who has the eyes to see them.

Skepticism is the highest duty and blind faith the one unpardonable sin.

Tolerably early in life I discovered that one of the unpardonable sins, in the eyes of most people, is for a man to go about unlabeled. The world regards such a person as the police do an unmuzzled dog.

Whatever evil voices may rage, Science, secure among the powers that are eternal, will do her work and be blessed.

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.

Science seems to me to teach in the highest and strongest manner the great truth which is embodied in the Christian conception of entire surrender to the will of God. Sit down before fact as a little child, be prepared to give up every preconceived notion, follow humbly wherever and to whatever abysses nature leads, or you shall learn nothing. I have only begun to learn content and peace of mind since I have resolved at all risks to do this.

I conceive that the leading characteristic of the nineteenth century has been the rapid growth of the scientific spirit, the consequent application of scientific methods of investigation to all the problems with which the human mind is occupied, and the correlative rejection of traditional beliefs which have proved their incompetence to bear such investigation.