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)