"The electron is an elementary particle, but it is not a 'thing' in the usual sense of the word."

"The electron is not a 'thing' in the usual sense of the word. It is a system of relationships."

"Our task is not to penetrate the essence of things, but to develop concepts which allow us to talk in a productive way about phenomena."

"We are all agreed that your theory is crazy. The question which divides us is whether it is crazy enough to have a chance of being correct."

"There are some things so serious that you have to laugh at them."