I act with complete certainty. But this certainty is my own.

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.

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

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

Nowadays it is the fashion to emphasize the horrors of the last war. I didn't find it so horrible. There are just as horrible things happening all round us today, if only we had eyes to see them.

What has history to do with me? Mine is the first and only world! I want to report how I find the world. What others have told me about the world is a very small and incidental part of my experience. I have to judge the world, to measure things.

Tell them I've had a wonderful life.