The trouble with theory in biology is it's not like that in physics, there's no way you can use it. You see… I mean, Leó Szilárd used to tell me that the one thing that happened when he went into biology is he couldn't take a nice bath. When he was a physicist, he could go into a bath and he could lie there for three hours and he could think about physics, but he said when he went into biology, no sooner did he get in the bath then he'd have to get out and look up another fact. So he was always unable then to take a... a relaxed bath, and I think that is the nature, because you have to ask yourself, who... you know, what had this all been about, because this is one of those remarkable things in biology that is, you know, absolutely true, yet absolutely vacuous. There's nothing you can do about it. I mean, it tells you how things might work; it doesn't tell you how you can make a mouse. That's in the end… we're always preoccupied with these questions of detail. So that's… but I think, you know, having had this connection with this kind of thinking, having, you know, tried to teach myself enough mathematics at least to be able to deal with a mathematical argument, but I think, you know, the thing that I've always realised I'm much better at is actually, you know, doing the real thing in a lab.