Grip the nettle firmly and it will become a stick with which to beat your enemy.

To test a perfect theory with imperfect instruments did not impress the Greek philosophers as a valid way to gain knowledge.

To surrender to ignorance and call it God has always been premature, and it remains premature today.

Today's science fiction is tomorrow's science fact.

It is precisely because it is fashionable for Americans to know no science, even though they may be well educated otherwise, that they so easily fall prey to nonsense.

I'm not a speed reader. I'm a speed understander.

He had read much, if one considers his long life; but his contemplation was much more than his reading. He was wont to say that if he had read as much as other men he should have known no more than other men.