Niels Bohr, fully Aage Niels Bohr

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

Any development of knowledge of the rules of nature which may help to give greater command of the powers of nature holds the hope of improving the living conditions of mankind; but also holds dangers which put our entire civilization to a serious test. The responsibilities, however, that these dangers are defeated in the right way, rests not only upon the scientist but must be shared by all circles of every nation.

An independent reality in the ordinary physical sense can neither be ascribed to the phenomenon nor to the agencies of observation.

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

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

One of the favorite maxims of my father was the distinction between the two sorts of truths, profound truths recognized by the fact that the opposite is also a profound truth, in contrast to trivialities where opposites are obviously absurd.

Every sentence I utter must be understood not as an affirmation but as a question.