Sometimes the child in one behaves a certain way and the rest of oneself follows behind, slowly shaking its head.

If anybody says he can think about quantum physics without getting giddy, that only shows he has not understood the first thing about them.

One must always do what one really cannot.

No paradox, no progress.

Anybody who is not shocked by this subject has failed to understand it. [of quantum mechanics]

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.

One thought spectra are marvellous, but it is not possible to make progress there. Just as if you have the wing of a butterfly then certainly it is very regular with the colors and so on, but nobody thought one could get the basis of biology from the coloring of the wing of a butterfly.