born 1933 in Stuttgart, studied mathematics and physics as a teacher at the Technical University of Stuttgart. 20 years experience as an upper school teacher, especially at the Freie Waldorfschule in Marburg/Lahn. From 1978-1989 lecturer at the Institute for Waldorf Education in Witten-Annen/Ruhr. From 1990-2003 Head of the Mathematical-Astronomical Section at the Goetheanum. Lectures and courses in Europe and South America. He died on 1 February 2019.