Richter began to use glass in his work in 1967, when he made `4 Panes of Glass?. In that work, each pane was framed and fixed to a stand, so that one could look through them individually. It had a strong cerebral content, in keeping with the contemporary Conceptual Art movement, but it also had a certain dead-pan humour. What are paintings, after all, it seemed to say, but windows on the world? ?11 Panes of Glass?, made almost forty years later, is much less conceptual. By stacking them up, one after another, Richter is able to play with glass?s ability, both to be looked through, and to reflect. Because there are multiple panes, the transparency is incrementally affected by the reflectivity of the glass. The blurring effect is similar to that found in Richter?s photo-paintings.