“It is an amusing jew d’esprit to take a philosopher’s ten or twenty volumes and try to compress them to postcard length. My proposal for doing this to Kant’s will be disappointing, since hardly anyone nowadays will deny the sentence but many will deny that it is the seminal thought in Kant. But it was a highly disputable proposition in his day, and I think that some of the lasting importance of Kant is shown by the fact that it is no longer disputed. The sentence would be: In order to know and to act, it is necessary both to see and to think.”