“There is no credulity so eager and blind as the credulity of covetousness, which, in its universal extent, measures the moral misery and the intellectual destitution of mankind.”

“One of the chief obstacles to intelligence is credulity, and credulity could be enormously diminished by instruction in the prevalent forms of mendacity.”

“I believe all this, and much, much more, because I guess it is my duty to. But I pay a price for my gaga credulity, which I want to describe as a sort of intellectual seasickness.”

“Learn to be as analytical about things of which you are credulous as you are of those which you criticise.”

“That day, I began to be incredulous. Or, rather, I regretted having been credulous. I regretted having allowed myself to be borne away by a passion of the mind. Such is credulity. ”

“Credulous: having views about the world, the universe and humanity's place in it that are shared only by very unsophisticated people and the most intelligent and advanced mathematicians and physicists.”