I act with complete certainty. But this certainty is my own.

It would strike me as ridiculous to want to doubt the existence of Napoleon; but if someone doubted the existence of the earth 150years ago, perhaps I should be more willing to listen, for now he is doubting our whole system of evidence.

Hegel seems to me to be always wanting to say that things which look different are really the same. Whereas my interest is in showing that things which look the same are really different. I was thinking of using as a motto for my book a quotation from King Lear: 'I’ll teach you differences'. ... 'You’d be surprised' wouldn’t be a bad motto either.

For a truly religious man nothing is tragic.

Philosophy, as we use the word, is a fight against the fascination which forms of expression exert upon us.

It is an hypothesis that the sun will rise tomorrow: and this means that we do not know whether it will rise.

Courage, not cleverness; not even inspiration, is the grain of mustard that grows up to be a great tree.