I had an extraordinary run of good fortune – I think I’ve mentioned this before – when I was in college of just meeting people who knew a lot about exactly what I happened to be interested in at the moment. And as I mentioned earlier, I was very strongly influenced by my accidental encounter with the great book by Nicolas Rashevsky called Mathematical Biophysics. I just happened to find it in a library and it had articles about applying mathematics to different aspects of biology. There would be a chapter on... how does a cell divide? Or how… what kind of physical system could cause a cell to contract at the equator and break into two parts without spilling all its contents? Just lovely little questions that any child could see... that’s… that's a question. How could it work? How could a nerve fiber conduct a signal? Chemical reactions might seem too slow to go at 100 meters per second so… or 10 meters per second or whatever it is. What’s the trick? This book was full of different applications of ordinary mathematics to biological problems. I’ve never seen anything like that. And one of them was about learning machines and neurons by McCulloch and Pitts.