“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 ...”

“The scientific spirit is of more value than its products, and irrationally held truths may be more harmful than reasoned errors.”

“What we call rational grounds for our beliefs are often extremely irrational attempts to justify our instincts.”

“With theology as a code of dogmas which are to be believed, or at any rate repeated, under penalty of present or future punishment, or as a storehouse of anaesthetics for those who find the pains o...”

“Wherever sufficiently numerous series of the remains of any given group, which has endured for a long space of time, are carefully examined, their morphological relations are never in discordance w...”

“I am too much of a skeptic to deny the possibility of anything.”

“I do not know what I may appear to the world, but to myself I seem to have been only like a boy playing on the sea-shore, and diverting myself in now and then finding a smoother pebble or a prettie...”

“To know the history of science is to recognize the mortality of any claim to universal truth. ”

“The scientist only imposes two things, namely truth and sincerity, imposes them upon himself and upon other scientists.”