When Anselm Kiefer made his lead airplanes twenty years ago, they were laden, as were all of his creations, with metaphors of war, violence, history, and, ultimately, death. Distantly resembling the planes used in World War II air battles, Kiefer’s earthbound aircraft with a polyhedron on one wing (Melancholia, 1990–91) or with gigantic books made of lead sheets on both (Angel of History, 1989) eloquently insinuated the unbearable weight of a ruinous history and a reflection on the unending process of mourning. If Kiefer’s monumental installations were an effective prescription for those viewers