One can measure the importance of a scientific work by the number of earlier publications rendered superfluous by it

Physics is much too hard for physicists.

For us there is no ignorabimus, and in my opinion none whatever in natural science. In opposition to the foolish ignorabimus our slogan shall be: "We must know - we will know!"

[On Cantor's work:] The finest product of mathematical genius and one of the supreme achievements of purely intellectual human activity.

We ought not to believe those who today, adopting a philosophical air and with a tone of superiority, prophesy the decline of culter and are content with the unknowable in a self-satisfied way. For us there is no unknowable, and in my opinion there is also non whatsoever for the natural sciences. In place of this foolish unknowable, let our watchword on the contrary be: we must know - we shall know.

Geometry is the most complete science.

He who seeks for methods without having a definite problem in mind seeks in the most part in vain.