The depressed man lives in a depressed world.

A main cause of philosophical disease-an unbalanced diet: one nourishes one's thinking with only one kind of example.

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.

Don't get involved in partial problems, but always take flight to where there is a free view over the whole single great problem, even if this view is still not a clear one.

Philosophy can be said to consist of three activities: to see the commonsense answer, to get yourself so deeply into the problem that the common sense answer is unbearable, and to get from that situation back to the commonsense answer.

You must always be puzzled by mental illness. The thing I would dread most, if I became mentally ill, would be your adopting a common sense attitude; that you could take it for granted that I was deluded.

Don't ask what it means, but rather how it is used.