In these days, finding a book that will introduce you to a subject is quite difficult. Most people today only learn by going to courses, they have to have a course of instruction, they have to have a lecture, they have to go to a summer course, the whole idea of learning by yourself now is absent. I noticed that when I wanted to learn a new subject like computation – the theory of computation – I got a book and read this book until I found the way to read it, for me. That is, the author thinks he's got the right way of telling you about the subject, but in fact I find no, I have to start with chapter seven, then go back and read the first half of chapter one, then go back, then go and read the second half of chapter 10. And in that way I create my own path through this. And I think that is very important, because it's the way you construct your own knowledge which is important to you. Francis read a lot; he read all of Hubel and Wiesel's papers. He found it very difficult. He also led... read a lot of the anatomy of the brain. And in fact for the last 30 years, I think, Francis has done very little except read in order to acquire the background to deal with such an immense problem. So perhaps his mind is now rotten.