Only one absolute certainty is possible to man, namely that at any given moment the feeling which he has exists.

I have never had the least sympathy with the a priori reasons against orthodoxy, and I have by nature and disposition the greatest possible antipathy to all the atheistic and infidel school. Nevertheless I know that I am, in spite of myself, exactly what the Christian would call, and, so far as I can see, is justified in calling, atheist and infidel.

Oh devil! truth is better than much profit. I have searched over the grounds of my belief, and if wife and child and name and fame were all to be lost to me one after the other as the penalty, still I will not lie.

If a man cannot see a church, it is preposterous to take his opinion about its altar-piece or painted window.

The foundation of morality is to have done, once and for all, with lying.

The scientific imagination always restrains itself within the limits of probability.

Nothing can be more incorrect than the assumption one sometimes meets with, that physics has one method, chemistry another, and biology a third.