[2] In his youth he was a member of the Communist Party of Denmark, but in the 1930s he was not active in the political arena due to his studies in medicine.

[2] During the Second World War and the German occupation of Denmark, he played a strategic role in the Danish resistance movement.

In 1942, he helped to set up the Frit Danmark, the illegal non-partisan resistance newspaper, and became an active member of the Danish Freedom Council (Frihedsrådet) in 1943.

He was arrested by the Gestapo in October 1944 but escaped in March 1945 after their headquarters in the Shell building were bombed by the Royal Air Force.

He was rector during the protests of 1968 and in cooperation with the students he made democratic reforms of university governance.