In the intellectual discussion circle Berliner Mittwochsgesellschaft (1863–1944), member since 1937, he met with scientists like Werner Heisenberg, Ferdinand Sauerbruch, Eugen Fischer and Eduard Spranger and also with some of the people, who planned to overthrow the NS-regime in the 20 July plot of 1944: Johannes Popitz, Ulrich von Hassell, Jens Jessen and General Ludwig Beck.