“The fact that an opinion has been widely held is no evidence whatever that it is not utterly absurd.”

“Wisdom is not wisdom when it is derived from books alone.”

“Why not whip the teacher when the pupil misbehaves?”

“I am persuaded that this method [for calculating the volume of a sphere] will be of no little service to mathematics. For I foresee that once it is understood and established, it will be used to discover other theorems which have not yet occurred to me, by other mathematicians, now living or yet unborn.”

“If you can't say anything nice, then don't say anything at all.”

“It is one thing to show a man that he is in an error, and another to put him in possession of the truth.”

“Only that education deserves emphatically to be termed cultivation of the mind which teaches young people how to begin to think.”