"I have tried lately to read Shakespeare, and found it so intolerably dull that it nauseated me."
"Linnaeus and Cuvier have been my two gods... but they were mere schoolboys to old Aristotle."
"He who understand[s] baboon[s] would do more towards metaphysics than Locke."
- "The sight of a feather in a peacock's tail, whenever I gaze at it, makes me sick!" (More on Darwin's skepticism of beauty here.)
"An American monkey, after getting drunk on brandy, would never touch it again, and thus was wiser than many men."
"We stopped looking for monsters under our bed when we realized that they were inside us."
"I feel most deeply that the whole subject [of a divine creator] is too profound for the human intellect. A dog might as well speculate on the mind of Newton. Let each man hope and believe what he can."
"But I am very poorly today & very stupid & hate everybody & everything. One lives only to make blunders."
"It was a very stupid blunder on my part... I shall, of course not allude to the subject, which I rather grieve about, as I wished it to be true; but alas a scientific man ought to have no wishes, no affections—a mere heart of stone."
"Often a cold shudder has run through me, and I have asked myself whether I may have not devoted myself to a fantasy."
"I am dying by inches, from not having anybody to talk to about insects..."