Man is a rational animal – so at least I have been told. Throughout a long life, I have looked diligently for evidence in favour of this statement, but so far I have not had the good fortune to come across it, though I have searched in many countries spread over three continents.

The essence of the liberal outlook lies not in what opinions are held, but in how they are held; instead of being held dogmatically, they are held tentatively, and with a consciousness that new evidence may at any moment lead to their abandonment.

Drunkeness is temporary suicide: the happiness that it brings is merely negative, a momentary cessation of unhappiness.

To be without some of the things you want is an indispensable part of happiness.

I think we ought always to entertain our opinions with some measure of doubt. I shouldn't wish people dogmatically to believe any philosophy, not even mine.

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.

If everything has a cause, then God must have a cause. If there can be anything without a cause, it may just be the world as God.