Neils Bohr

We must be clear that when it comes to atoms, language can be used only as in poetry. The poet, too, is not nearly so concerned with describing facts as with creating images and establishing mental connections.

Isolated material particles are abstractions, their properties being definable and observable only through their interaction with other systems.

Two sorts of truth: trivialities, where opposites are obviously absurd, and profound truths, recognised by the fact that the opposite is also a profound truth.

Anyone who is not shocked by quantum theory has not understood it.