Sigmar Polke (born 1941) recently completed a series of 12 windows for the Grossmünster cathedral in Zürich, setting new standards for the mutual relationship between art and church. One group of seven Romanesque windows shows luminous mosaics of thinly sliced agate, some of it artificially colored, to produce pulsating blocks of back-lit color. Says Marina Warner, "The interior of rocks opens not only on unexpected colors... on once imprisoned now scintillating rays and gleams, but it also tunnels into the past, into the distant past of geological and cosmological millennia." For the remaining five windows, Polke designed images of figures from the Old Testament, based on medieval illuminations, which have themselves undergone transformation in the course of their long journey through time. Polke's figures now appear as radiantly contemporary icons created in colored glass, using a variety of traditional and customized techniques devised especially for this project.