Not far from the invention of fire we must rank the invention of doubt.

We are prone to see what lies behind our eyes, rather than what apprears before them.

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

We live in a world which is full of misery and ignorance, and the plain duty of each and all of us is to try to make the little corner he can influence somewhat less miserable and somewhat less ignorant than it was before he entered.

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

I protest that if some great Power would agree to make me always think what is true and do what is right, on condition of being turned into a sort of clock and would up every morning before I got out of bed, I should instantly close with the offer.

Every great advance in natural knowledge has involved the absolute rejection of authority.