The years of searching in the dark for a truth that one feels but cannot express, the intense desire and the alternations of confidence and misgiving until one breaks through to clarity and understanding, are known only to him who has experienced them himself.

Though our conduct seems so very different from that of the higher animals, the primary instincts are much alike in them and in us.

The thing is, not to stop questioning.

Stupidity is a personal achievement which transcends national boundaries.

If you're not sure why you're doing something, you can never do enough of it. Imagination is more important than knowledge.

Since I have introduced this term I had always a bad conscience. . . . I cannot help to feel it strongly and I am unable to believe that such an ugly thing should be realized in nature.

Women marry men hoping they will change. Men marry women hoping they will not.