Yves-Alain Bois at Artforum:
My first encounter with him is a case in point. It was during the installation of his retrospective at the Centre Pompidou in 1981. Ryman sat on top of a large unopened crate, alone in the vast Galeries Contemporaines on the ground floor. Many works were resting against the walls; others were in chariots. Crates and wrapping material were strewn everywhere. After introducing myself I asked him what he was doing. “Waiting,” he said calmly. “Waiting for the electricians to fix the lighting.” Finding out that he had been doing so for a good half hour, I concluded that something was wrong, perhaps lost in translation—surely the electricians’ coffee or cigarette break was not supposed to take that long—and I rushed upstairs to the curatorial office. (At the time, it was located on the third floor.) It turned out that the electricians were waiting elsewhere for Ryman’s call, to be transmitted via the guard in attendance, that he was ready for them to come. They were waiting for his signal that he had determined where the paintings should hang; he was waiting for them to provide absolutely evenly lit walls so that he could start experimenting with the placement of his works.
more here.