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.

The problems are solved, not by giving new information, but by arranging what we have always known.

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

The common behavior of mankind is the system of reference by means of which we interpret an unknown language.

I won't say 'See you tomorrow' because that would be like predicting the future, and I'm pretty sure I can't do that.

What we cannot speak about we must pass over in silence.

All philosophy is a 'critique of language' (though not in Mauthner's sense). It was Russell who performed the service of showing that the apparent logical form of a proposition need not be its real one.