"I had a long conversation with Einstein a week before he died, which is something that may be of interest historically. ... the only one I had with him took place at the end of my year at the Princeton Institute, April 1955 … It was literally a week before he died, and I was with him for over an hour and a half … I started out a bit nervous of course. I'd read that he had a hearty laugh and a simple sense of humor, so I thought I'd start out in the following way. Originally, of course, the very phrase was Einstein's own phrase for that idea. And he'd used the principle as the guiding light for constructing general relativity. But he later came to feel that the principle wasn't so important, and in the autobiographical notes which he wrote for that … he had said that he came to disown Mach's Principle. So knowing that, I went to see him and I said, "Professor Einstein, I've come to talk about Mach's PrincipIe and I've come to defend your former self … against your later self." And it worked: he said, "Ho, ho, ho, that is gut, Ja!" Like that, really laughed. So that put me a bit at my ease. So then I talked about my way of doing Mach's Principle and he talked about his work and his doubts about quantum theory and so on. It was a wonderful experience."