In science the successors stand upon the shoulders of their predecessors; where one man of supreme genius has invented a method, a thousand lesser men can apply it. ... In art nothing worth doing can be done without genius; in science even a very moderate capacity can contribute to a supreme achievement.

To save the world requires faith and courage: faith in reason, and courage to proclaim what reason shows to be true.

The trouble with the world is that the stupid are cocksure and the intelligent are full of doubt.

Pure mathematics consists entirely of assertions to the effect that, if such and such a proposition is true of anything, then suchand such another proposition is true of that thing.... Thus mathematics may be defined as the subject in which we never know what we are talking about, nor whether what we are saying is true.

To avoid the various foolish opinions to which mankind are prone, no superhuman genius is required. A few simple rules will keep you, not from all error, but from silly error.

Thomas Aquinas states parenthetically, as something entirely obvious, that men are more rational than women. For my part, I see no evidence of this.

Worry is a form of fear.