I don't think I've ever really done astrophysics. I have been interested in it all my life and I've been... I've been a cheerleader but not a player. I mean, the two greatest things I did for the Institute here in Princeton were bringing two people here. First Stroemgren, and second, Bahcall, who are both of them great astrophysicists. Stroemgren started astrophysics here, I forget just when, in the 1960s I think, and I was instrumental in bringing him here, and he was wonderful in getting things started. He attracted very good people, he had excellent relations with Princeton University, and he had this ability to do both observation and theory. So he would... he would go away to Kitt Peak to observe and come back and work out his observations here, and so I loved Stroemgren and I was very close to him, but I never did astrophysics myself. He was... he was the one who did it, but I certainly gave him a lot of encouragement. And then 10 years later after Stroemgren went back to Denmark we had to find somebody to replace him,and it was my initiative that brought John Bahcall here, and John Bahcall, of course, was a marvellous success too. He's very different from Stroemgren, but he's done equally well, and he's been father of neutrino astronomy; he pushed neutrino astronomy with his friend Ray Davis right from the start, which has been a very, very hard struggle, but has now, after 30 years, finally begun to flourish. So we're making big discoveries now with neutrino detectors underground, which are essentially brain children of John Bahcall. In addition to that of course, he does many other kinds of astrophysics. So I have been all the time, all the way through, I've been a bystander. I love to sit at the astronomers' table at lunch and hear what they're doing, but I am not able to do very much myself because it's not mathematical enough for me. It's... very much of the work is imaginative, very, very much imaginative. I mean, in theoretical work in astrophysics you invent a new model and you do some rough estimates and then you publish, and three months later there's a new observation which makes it obsolete. It's a style of work which I'm not really able to compete with myself. It's very quick and dirty and it's done very well by lots of people here.