Thinking in isolation and with pride ends in being an idiot.

Unfortunately, 19th-century scientists were just as ready to jump to the conclusion that any guess about nature was an obvious fact, as were 17th-century sectarians to jump to the conclusion that any guess about Scripture was the obvious explanation . . . . and this clumsy collision of two very impatient forms of ignorance was known as the quarrel of Science and Religion.

Misers get up early in the morning; and burglars, I am informed, get up the night before.

The old assumption of the approximate impossibility of war really rested on a similar assumption about the impossibility of evil-and especially of evil in high places.

There is not really any courage at all in attacking hoary or antiquated things, any more than in offering to fight one's grandmother. The really courageous man is he who defies tyrannies young as the morning and superstitions fresh as the first flowers. The only true free-thinker is he whose intellect is as much free from the future as from the past.

Men rush toward complexity; but yearn for simplicity.

The whole modern world has divided itself into Conservatives and Progressives. The business of Progressives is to go on making mistakes. The business of Conservatives is to prevent mistakes from being corrected.