“Everything we call real is made of things that cannot be regarded as real.”

“The very nature of the quantum theory ... forces us to regard the space-time coordination and the claim of causality, the union of which characterizes the classical theories, as complementary but exclusive features of the description, symbolizing the idealization of observation and description, respectively.”

“An expert is a person who has made all the mistakes that can be made in a very narrow field.”

“An expert is a man who has made all the mistakes which can be made in a very narrow field.”

“Those who are not shocked when they first come across quantum theory cannot possibly have understood it.”

“How wonderful that we have met with a paradox. Now we have some hope of making progress.”

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