Someone who knows too much finds it hard not to lie.

Language disguises thought.

If you tried to doubt everything you would not get as far as doubting anything. The game of doubting itself presupposes certainty.

Proof, one might say, does not merely shew that it is like this, but: how it is like this. It shows how 13+14 yield 27.

I am sitting with a philosopher in the garden; he says again and again 'I know that that’s a tree', pointing to a tree that is near us. Someone else arrives and hears this, and I tell him: 'This fellow isn’t insane. We are only doing philosophy.

In order to draw a limit to thinking, we should have to think both sides of this limit.

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.