Insofar as mathematics is true, it does not describe the real world. Insofar as it describes the real world, it is not true.

It is my conviction that pure mathematical construction enables us to discover the concepts and the laws connecting them, which gives us the key to the understanding of nature ... In a certain sense, therefore, I hold it true that pure thought can grasp reality, as the ancients dreamed.

We still do not know one thousandth of one percent of what nature has revealed to us.

Why does this magnificent applied science which saves work and makes life easier bring us so little happiness? ... The simple answer runs: 'Because we have not yet learned to make sensible use of it.'

The ancients knew something, which we seem to have forgotten.

Nobody knows how the stand of our knowledge about the atom would be without him. Personally, [Niels] Bohr is one of the amiable colleagues I have met. He utters his opinions like one perpetually groping and never like one who believes himself to be in possession of the truth.

I live my daydreams in music.