During the winter of 1940–1941, the German pastor and theologian Dietrich Bonhoeffer (1906–1945) spent some months at the monastery as the friend and guest of the Abbot. Like Bonhoeffer, a number of those in the Ettal community were involved in the conspiracy against Hitler. While at Ettal, Bonhoeffer also worked on his book "Ethics". Catholic priest Rupert Mayer was kept at the Abbey under house arrest from 1939 to 1945 by the Nazis to prevent him from further anti-Nazi preaching.