I met Grothendieck only once, in the summer of 1971. There was a NATO-sponsored logic conference in, I think, England and some people decided to sponsor a counter conference that would have no connection with anything military. It was held in a private boarding school in a town called Uldum, Denmark which is something like 50 km south of Aarhus. G. had given up mathematics at that time and agreed to come presumably because it was anti-military. I was spending half of that summer in Aarhus and I had a car, so on the day G. was scheduled to speak, I got in my car and drove down. His talk was interesting. As I recall, he stated the Giraud axioms for a topos and then said that to him, they looked an awful lot like set theory and logicians should study them from that point of view. Maybe he said intuitionistic set theory; I don't recall. Well the Giraud axioms didn't--and don't--look much like set theory to me. So at the end of his talk I asked him if he was familiar with the Lawvere-Tierney axioms for a topos, which looked a lot more like set theory than the Giraud axioms. He said that he didn't know what they were and asked me to come to the board and explain them. Which I did (I added complete and cocomplete to recover the original definition that G. had used). He agreed that looked a lot more like set theory. A few logicians did study toposes, but whether they were motivated by G.'s lecture, I can't tell you. After that we had an hour-long discussion of Survivre, which didn't convince me. Bill can correct me if I am wrong, but I recall that at the Nice meeting a year earlier, Bill had tried to tell him about elementary toposes, but G. wasn't interested in anything mathematical. Michael [For admin and other information see: http://www.mta.ca/~cat-dist/ ]