..... if anybody says he can think about quantum theory without getting giddy it merely shows that he hasn't understood the first thing about it!
Quoted in Otto R. Frisch, What little I remember (1979), p.95

... the old saying of the two kinds of truth. To the one kind belongs statements so simple and clear that the opposite assertion obviously could not be defended. The other kind, the so-called "deep truths", are statements in which the opposite also contains deep truth.
Niels Bohr, Discussion with Einstein on epistemological problems in atomic physics in P.A. Schilpp (ed.) Albert Einstein: Philosopher--Scientist, (1949), 240

... when searching for harmony in life one must never forget that in the drama of existence we are ourselves both actors and spectators.
Niels Bohr, Discussion with Einstein on epistemological problems in atomic physics in P.A. Schilpp (ed.) Albert Einstein: Philosopher--Scientist, (1949), 236

How wonderful that we have met with a paradox. Now we have some hope of making progress.
Quoted in R. Moore, Niels Bohr, the Man and the Scientist (1967),140

What is it that we human beings ultimately depend on? We depend on our words. We are suspended in language. Our task is to communicate experience and ideas to others.
Quoted in Aage Petersen, The Philosophy of Niels Bohr, in Bulletin of the Atomic Scientists 1963, XIX, 7, p.10

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.
Quoted in Aage Petersen, The Philosophy of Niels Bohr, in Bulletin of the Atomic Scientists 1963, XIX, 7, p.12

Contraria sunt complementa (Opposites are complementary)
Motif on Niels Bohr's coat of arms, Order of the Elephant

Niels Bohr Archive, Copenhagen: Mail address: nba at nbi.dk Web address: www.nba.nbi.dk Last updated: 2015