"The improver of natural knowledge absolutely refuses to acknowledge authority, as such. For him, skepticism is the highest of duties; blind faith the one unpardonable sin."

"The only question which any wise man can ask himself, and which any honest man will ask himself, is whether a doctrine is true or false."

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

"Logical consequences are the scarecrows of fools and the beacons of wise men."

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

"There is but one right, and the possibilities of wrong are infinite."

"The results of political changes are hardly ever those which their friends hope or their foes fear."

"If a little knowledge is dangerous, where is the man who has so much as to be out of danger?"

"The medieval university looked backwards; it professed to be a storehouse of old knowledge. The modern university looks forward, and is a factory of new knowledge."

"My business is to teach my aspirations to confirm themselves to fact, not to try and make facts harmonize with my aspirations."

"Time, whose tooth gnaws away everything else, is powerless against truth."

"I took thought, and invented what I conceived to be the appropriate title of 'agnostic'."

"The ultimate court of appeal is observation and experiment... not authority."

"The doctrine that all men are, in any sense, or have been, at any time, free and equal, is an utterly baseless fiction."

"The rung of a ladder was never meant to rest upon, but only to hold a man's foot long enough to enable him to put the other somewhat higher."

"Misery is a match that never goes out."

"Proclaim human equality as loudly as you like, Witless will serve his brother."

"It is because the body is a machine that education is possible. Education is the formation of habits, a superinducing of an artificial organization upon the natural organization of the body."

"Make up your mind to act decidedly and take the consequences. No good is ever done in this world by hesitation."

"Surely there is a time to submit to guidance and a time to take one's own way at all hazards."

"It is not who is right, but what is right, that is of importance."

"The child who has been taught to make an accurate elevation, plan, and section of a pint pot has had an admirable training in accuracy of eye and hand."