Ivan Illich (1926-2002), a philosopher, theologian, and historian, was considered one of the most important and lucid thinkers of the second half of the twentieth century. He was the author of several books, including Celebration of Awareness, Medical Nemesis, Gender, and In the Vineyard of the Text. He was Visiting Professor of Philosophy and of Science, Technology, and Society at Penn State University in the 1980s and 1990s.