“Who can refute a sneer?”

“It is certainly not the least charm of a theory that it is refutable; it is precisely thereby that it attracts the more subtle minds. It seems that the hundred-times-refuted theory of the "free will" owes its persistence to this charm alone; some one is always appearing who feels himself strong enough to refute it.”

“No friend had I made there, but I wasn't with this group to make friends, and besides, he sneered too much. I've found that people who sneer are almost always sneering at me.”

“You can easily see what and endless, wearisome and fruitless task it would be if I were to refute all the unconsidered objections of people who pigheadly contradict everything I say.”

“Science cannot destroy the consciousness of freedom, without which there is no morality and no art, but it can refute it.”

“One cannot refute Christianity; one cannot refute a disease of the eye.”