The subject does not belong to the world; rather, it is a limit of the world.

Where our language suggests a body and there is none: there, we should like to say, is a spirit.

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.

A philosopher who is not taking part in discussions is like a boxer who never goes into the ring.

How hard I find it to see what is right in front of my eyes!

This procedure [selecting the simplest law], however, has no logical justification but only a psychological one.

I give no sources, because it is indifferent to me whether what I have thought has already been thought before me by another.