The historian Willy Cohn kept a diary from his youth till his death in 1941. The book contains the entries written from 1933 till 1941, which had been hidden in Berlin by family members. This is a comprehensive document containing deep, serious descriptions. The diary was written from a subjective point of view, but also from the point of view of a professional historian. Cohn described the initial shock felt when the Nazis came into power, and the deep disappointment with the disappearance of the humanistic and democratic values he believed in which collapsed right in front of his eyes, as well as the move of many acquaintances to ‘the other side’. This reality created an ongoing conflict with the German patriotism which was part of his personality and became empowered even more during his military service in World War I.