Francis was... Francis Crick, of course, shared an office with Sydney Brenner, and I remember going to visit them, and on the wall of the office was a big notice: 'Reading Rots the Mind'. And he and Sydney had a special arrangement, and that was, if any or either of them had an idea, no matter how silly it was, they would agree to discuss it in detail, to make sure that there wasn’t something in it. And Sydney pointed out that in order to make progress in a particular area, you must not know too much about the subject, because that closes your mind; you want to come to a subject where you don’t know very much and you want to bring new ideas into it. And that’s exactly what he did by bringing in the nematode worm as a model for developmental biology. So he felt... he felt very strongly that knowing too much about a subject you wouldn’t make real progress there, because you’d be trapped by the current ideas.