Berlin, designed by Speer in 1938 in honor of the Unknown Soldier. In 1984–85, he made a series of works on paper incorporating manipulated black-and-white photographs of desolate landscapes with utility poles and power lines. Such works, like Heavy Cloud (1985), were an indirect response to the controversy in West Germany in the early 1980s about NATO's stationing of tactical nuclear missiles on German soil and the placement of nuclear fuel processing facilities. By the mid-1980s, Kiefer's themes widened from a focus on Germany's role in civilization to the fate of art and culture in general. His work became more sculptural and involved not only national identity and collective memory, but also occult symbolism, theology and mysticism. The theme of all the work is the trauma experienced by entire societies, and the continual rebirth and renewal in life. During the 1980s his paintings became more physical, and featured unusual textures and materials. The range of his themes broadened to include references to ancient Hebrew and Egyptian history, as in the large painting Osiris and Isis (1985–87). His paintings of the 1990s, in particular, explore the universal myths of existence and meaning rather than those of national identity. From 1995 to 2001, he produced a cycle of large paintings of the cosmos. He also started to turn to sculpture, although lead still remains his preferred medium. Over the years Kiefer has made many unusual works, but one work stands out among the rest as particularly bizarre—that work being his 20 Years of Solitude piece. Taking over 20 years to create (1971–1991), 20 Years of Solitude is a ceiling-high stack of hundreds of white-painted ledgers and handmade books, strewn with dirt and dried vegetation, whose pages are stained with the artist's semen. The word solitude in the title references the artists frequent masturbation onto paper during the 20 years it took to create. He asked American art critic Peter Schjeldahl to write a text for a catalog of the masturbation books. Schjeldahl attempted to oblige but ultimately failed in his endeavor. No other critic would take on the task, so the work has largely faded into obscurity. He would shock the art world yet again at a dinner party in May 1993. Kiefer and his second wife, Renate Graf, decorated a candlelit commercial loft in New York with white muslin, carpeted the floor with white sand, and staffed it with waiters dressed