Genius is talent in which character makes itself heard.

A tautology's truth is certain, a proposition's possible, a contradiction's impossible.

With my full philosophical rucksack I can only climb slowly up the mountain of mathematics.

Only when one thinks even much more madly than the philosophers can one solve their problems.

Resting on your laurels is as dangerous as resting when you are walking in the snow. You doze off and die in your sleep.

It is so characteristic, that just when the mechanics of reproduction are so vastly improved, there are fewer and fewer people who know how the music should be played.

The sense of the world must lie outside the world... What we cannot speak about we must remain silent about... What can be described can happen too, and what is excluded by the laws of causality cannot be described.