A Knight at the Opera examines the remarkable and unknown role that the medieval legend (and Wagner opera) Tannhauser played in Jewish cultural life in the nineteenth and early twentieth centuries. The book analyzes how three of the greatest Jewish thinkers of that era, Heinrich Heine, Theodor Herzl, and I. L. Peretz, used this central myth of Germany to strengthen Jewish culture and to attack anti-Semitism. Readers will see how Tannhauser evolves from a medieval knight to Peretz's pious Jewish scholar in the Land of Israel. The book also discusses how the founder of Zionism, Theodor Herzl, was so inspired by Wagner's opera that he wrote The Jewish State while attending performances of it. A Knight at the Opera uses Tannhauser as a way to examine the changing relationship between Jews and the broader world during the advent of the modern era, and to question if any art, even that of a prominent anti-Semite, should be considered taboo.