Niels Bohr

How wonderful that we have met with a paradox.  Now we have some hope of making progress.

The opposite of a fact is falsehood, but the opposite of one profound truth may very well be another profound truth.

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

There are two kinds of truth, small truth and great truth. You can recognize a small truth because its opposite is a falsehood. The opposite of a great truth is another truth.

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

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

Never express yourself more clearly than you are able to think.

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

A physicist visits a colleague and notices a horseshoe hanging on the wall above the entrance. 'Do you really believe that a horseshoe brings luck?' he asks. 'No,' replies the colleague, 'but I've been told that it works even if you don't believe in it.'

Prediction is extremely difficult. Especially about the future.