As a student in Vienna, he was briefly kept in custody by the Nazis in 1938 because of his opposition to the annexation of Austria into Greater Germany.[1] Later he moved to Frankfurt to study law, but he was recruited by the Wehrmacht in 1942. After spending several years in a Soviet POW camp, he returned to Germany in 1949 and started a career as a commentator. His wife was the Austrian journalist and author Thea Leitner.
At first, he focused on legal and sociological topics, but later he took medical and psychology-related subjects as his theme. His book So lernt man lernen (How to learn to learn), a practical manual on the psychology of learning, became a bestseller. In this often-cited book he described his Leitner System which uses flashcards for accelerated and increased learning by spaced repetition.
