Descartes’ cogito: `I think, therefore I am’. Can one know that one is thinking, but not know what one is thinking? Can one know that one exists, but not know what kind of being one is? If that is impossible, as it seems it is, doesn’t that imply that with the cogito already a whole frame, – of concepts, categories, etc. –, has to be assumed? But then what kind of claim to a foundation does the cogito make?