Calculus required continuity, and continuity was supposed to require the infinitely little; but nobody could discover what the infinitely little might be.

The dictum that human nature cannot be changed is one of those tiresome platitudes that conceal from the ignorant the depths of their own ignorance.

I think we ought always to entertain our opinions with some measure of doubt. I shouldn't wish people dogmatically to believe any philosophy, not even mine.

Never try to discourage thinking, for you are sure to succeed.

Mathematics rightly viewed possesses not only truth but supreme beauty.

Fools and fanatics are always so certain of themselves.

Religions that teach brotherly love have been used as an excuse for persecution, and our profoundest scientific insight is made into a means of mass destruction.