I never forget that I was once asked whether I would meet a man who was the President of The British Computing Society, and I said, sure, and he came up and we had lunch together in Cambridge. He says, 'I've been dying to meet you because we're interested in writing programs for banks. What we'd like to know is how does the biological system perform all these complicated things? Maybe there's some clues to us for programming'. I said, 'You know, I'm really delighted to meet you because I'm interested in how do these biological systems do all these complex things, and I thought well, maybe if I studied some complex programs for banks I would get some clues to explaining this'. So we both departed in great mutual ignorance, which is the best way. But I think this sort of thing did spark off an interest in my... of mine, which I still have, which is questions of the theory of elaborate systems, which I've never had time to work on properly. But I think there is... I mean, the first question about... in this field is: is there a theory of elaborate systems? I'm afraid I can't answer that yet, but I think there is a style of thinking that one has to use which escapes very much what, what we can do in, in our normal thought processes.