It is the hallmark of any deep truth that its negation is also a deep truth.

One must always do what one really cannot.

When asked ... [about] an underlying quantum world, Bohr would answer, 'There is no quantum world. There is only an abstract quantum physical description. It is wrong to think that the task of physics is to find out how nature is. Physics concerns what we can say about Nature.'

Anyone who can contemplate quantum mechanics without getting dizzy hasn't understood it.

The best weapon of a dictatorship is secrecy, but the best weapon of a democracy should be the weapon of openness.

There are two sorts of truth: trivialities, where opposites are clearly absurd, and profound truths, recognised by the fact that the opposite is also a profound truth

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