There was a lecture once a week in the afternoon, in the Jefferson Hall, and I remember wondering what would Phillipp Frank look like actually. And his appearance was better than any expectation I could possibly have had of him. He was short and he had a limp, because it turned out he'd had an encounter with a streetcar in Vienna when he was young. He had an accent, which was unplaceable. His mother tongue, I believe, was Austrian, or German Viennese, whatever. But he knew enormous numbers of languages and I always said that his languages were like the buried cities of Troy. You'd dig down and some language would pop up unexpectedly. And he used to try to do imitations of people. I don't know how successful they were, but he would tell stories about Einstein. He did these things like Einstein and Phillipp Frank were on a bridge in Vienna and Phillipp Frank would say, 'Und dere was I und auch there was Einstein auch. Und den dere was I und also dere was Einstein dere. I am quite certain it was Einstein dere and I auch. Und den we looked a book, and den I looked again, and dere was Einstein once again dere. Und Einstein said to me, “Phillipp, I do not like people”.' So I remember him telling stories of this kind. And I'd loved that course. I'd loved it. I had no idea I would probably be a physicist, but I just loved this course. And so I took a sequel to it, and then eventually I came to grade papers for Professor Frank, got to know him pretty well. He was an extraordinary person. So I realised that… because in his lectures, he would say, 'Well, now I'm going to make a sudden interval.' And there'd be an interval, and then after the interval, you could ask questions. But he would… people would go away, there'd be very few people left after the interval. And then he would say, 'well, for those of you who know a little mathematics'… and then he would do a little mathematical derivation. I knew nothing of any mathematics, calculus, I knew nothing of any of this. But I realised that if I was going to understand anything, I had to learn more mathematics. It was just evident to me that, you know, it's… I kind of had to do it.