‘Nationalism is an infantile disease. It is the measles of mankind.’ Albert Einstein’s deft avoidance of the question put to him in 1929 – whether he considered himself a German or a Jew – was prophetic of what would happen to his country in the following decade. He was just one of the many stars of Berlin, Europe’s dazzling, decadent centre of the arts and culture, whose spark would be dimmed or extinguished by Adolf Hitler.