Prediction is very difficult, especially about the future. - Niels Bohr

"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."

"There are trivial truths and there are great truths. The opposite of a trivial truth is plainly false. The opposite of a great truth is also true."

"You can recognize a small truth because its opposite is a falsehood. The opposite of a great truth is another truth."

"Stop telling God what to do with his dice."

"The opposite of a correct statement is a false statement. But the opposite of a profound truth may well be another profound truth."