It is a light-space modulator –not to be confused with the more simple plexiglass space-modulators. I tried to take photos of the  Light-Play Black White Grey at the recently closed Moholy-Nagy show at the Guggenheim, but the images didn’t come out well. Instead, I found this online on Youtube. The hard metalic contraption spins gently, casting light in such a way as to modify space by cutting up light. Created in 1930, this is, I believe, a reconstruction built in 2006. I’ll show it in seminar today, maybe alongside and simultaneously to Heidegger’s The Question Concerning Technology.”