The news of Michael Stolleis' death has affected us deeply. Stolleis was a great historian who left an impressive body of work, an astute and sensitive observer of contemporary history, and at the same time a much-loved colleague of the Max Planck Institute for the History of Science. As well as being involved in the presidential commission “History of the Kaiser Wilhelm Society in National Socialism” (1999–2005), he was a major supporter of the Research Program "History of the Max Planck Society" from its inception. His ideas and input were of great importance to us and will be very much missed.