Niels Bohr — "Anyone who is not shocked by quantum theory has not understood it."

"It is not possible to describe the world without describing ourselves."

"The atom is not a mechanical system, but a system of relationships."

"No, I certainly do not believe in this superstition. But you know, they say that it does bring luck even if you don't believe in it!"

"Every great and deep difficulty bears in itself its own solution. It forces us to change our thinking in order to find it."

"One must be clear that, as far as the atoms are concerned, we are not dealing with an analogy to everyday experience but with something quite different."