After 1945, the need to reconstruct old church windows presented artists with a new challenge. Stockhausen trusted primarily in "light that carries colour through a room and lets it become an immaterial force." This force, he believed, has the ability to help transcend borders, as in Ulm cathedral (1955 / 1956) where he, in 1986, preserved the memory of the sufferings in Treblinka, Auschwitz and Bergen-Belsen with his "Israel window." His "works...