The difference between ancients and moderns is that the ancients asked what have we experienced, and moderns asked what can we experience.

Some of the finest moral intuitions come to quite humble people. The visiting of lofty ideas doesn't depend on formal schooling.

Almost all new ideas have a certain aspect of foolishness when they are first produced.

In the study of ideas, it is necessary to remember that insistence on hard-headed clarity issues from sentimental feeling, as it were a mist, cloaking the perplexities of fact. Insistence on clarity at all costs is based on sheer superstition as to the mode in which human intelligence functions. Our reasonings grasp at straws for premises and float on gossamers for deductions.

Nature, even in the act of satisfying anticipation, often provides a surprise.

Religion will not regain its old power until it can face change in the same spirit as does science.

I will not go so far as to say that to construct a history of thought without profound study of the mathematical ideas of successive epochs is like omitting Hamlet from the play which is named after him. That would be claiming too much. But it is certainly analogous to cutting out the part of Ophelia. This simile is singularly exact. For Ophelia is quite essential to the play, she is very charming . . . and a little mad.