Every mathematician worthy of the name has experienced . . . the state of lucid exaltation in which one thought succeeds another as if miraculously . . . this feeling may last for hours at a time, even for days. Once you have experienced it, you are eager to repeat it but unable to do it at will, unless perhaps by dogged work. . . .
The thrill of creation which we experience which we experience when we see a masterpiece is not unlike the feeling of the artist who created it; such a work is a fragment of the world which he has annexed and which belongs to him alone.