Who the hell is Leo Baeck?"" There's an opening line to catch your eye--but no more arresting than the answer given to the OSS officer assigned to find Baeck in a Nazi concentration camp in 1945: ""The pope of the German Jews."" This was exaggeration, but it signified Baeck's high standing as a Jewish moral leader during the Nazi years. Baker tells Baeck's story in relation to the history of the German Jews down to his death as an expatriate in England in the 1950s. Restrained in manner but mentally energetic, Baeck became the most prominent rabbi in Berlin during some 30 years as spokesman of liberal, humanistic, morally rigorous Judaism. His vigorous attack on intellectual anti-Semitism, The Essence of Judaism, was a ""beacon to the Jewish people,"" summoning them toward a faith uniting tradition, duty, and mystery. At Hitler's ascension, Baeck's eminence grew dangerous, but he embraced the threat and assumed the presidency of the newly created National Council of German Jews, organizing educational, economic, and emigration programs as a first line of Jewish defense. The shocking anti-Semitic violence of Kristallnacht (1938) convinced Baeck that the Jews must flee, although he vowed to remain until ""I am the last Jew alive in Germany."" Baeck's life then becomes a lens through which Baker views the mounting Nazi hostilities against the Jews, together with the moral complicity of quiescent German Christians and the Jews' own disbelief that the nightmare could go on. Finally, in 1943, Baeck was himself arrested and taken to Theresienstadt, the ""model"" ghetto partially open to outside observers. There Baeck's leadership consisted in quiet organizing, dignified endurance, and enspiriting faith. Baker's narrative is scholarly and simple in tone, as it should be; and although chiefly a study in Jewish history, it is also a study in historical tragedy and moral will--and more substantial altogether than the previous biography by Albert J. Friedlander, which is chiefly an elaboration of Baeck's theological ideas.