The classifications made by philosophers and psychologists are like trying to classify clouds by their shape.

At the core of all well-founded belief lies belief that is unfounded.

Most of the propositions and questions to be found in philosophical works are not false but nonsensical.

There can never be surprises in logic.

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 truth of the thoughts that are here set forth seems to me unassailable and definitive. I therefore believe myself to have found, on all essential points, the final solution of the problems. And if I am not mistaken in this belief, then the second thing in which the value of this work consists is that it shows how little is achieved when these problems are solved.

My day passes between logic, whistling, going for walks, and being depressed. I wish to God that I were more intelligent and everything would finally become clear to me - or else that I needn't live much longer.