“All truths are bloody truths to me.”

“There are no facts, only interpretations.”

“When somebody dies we usually need reasons for consolation, not so much to alleviate our pain as to excuse ourselves for so readily feeling consoled.”

“But thus do I counsel you, my friends: distrust all in whom the impulse to punish is powerful! Distrust all those who talk much of their justice!”

“In a seriously intended intellectual emancipation a person's mute passions and cravings also hope to find their advantage.”

“But lest I should mislead any when I have my own head and obey my whims, let me remind the reader that I am only an experimenter.Do not set the least value on what I do, or the least discredit on what I do not, as if I pretended to settle any thing as true or false. I unsettle all things. No facts are to me sacred; none are profane; I simply experiment, an endless seeker with no Past at my back.”

“The power which resides in him is new in nature, and none but he knows what that is which he can do, nor does he know until he has tried.”

“The lessons of science should be experimental also. The sight of a planet through a telescope is worth all the course on astronomy; the shock of the electric spark in the elbow outvalues all theories; the taste of the nitrous oxide, the firing of an artificial volcano, are better than volumes of chemistry.”