The theologian, be he Jewish or Christian, perhaps even the agnostic philosopher, will be strongly inclined to define the phenomenon of Judaism in the singular, so as to enter into conceptual abstractions; he may be professionally obliged to do so. But the historian will prefer using the plural and talk of the phenomena of Judaism, thus remaining within the domain of strictly descriptive scholarship.

In the last analysis, any attempt to define that elusive “essence of judaism” that Jews and Gentiles, philo-Semites and anti-Semites have tried long to establish is doomed to failure if it takes as its starting point anything other than the fullness of all available historical phenomena. The historian, as distinct from the theologian, has a powerful case against overhasty generalizations. He will claim not to know the full facts. The fullness of Judaism, he says, has not realized itself. His argument will be a double one: Against the Christian theologian he will argue that there occurred no noticeable end of judaism with the birth of Christianity. Jewry still remained a changing, developing entity whose totality had not been exhausted with the emergence of the daughter religion. And the historian will have to argue against the Jewish theologian that he (the historian) cannot easily assimilate into his empirical method the concept of a revelation as a supernatural act that embraced once and for all the totality of all correct Jewish views and practice, and from which every Jewish phenomenon will have to be derived in order to be justified. The historian will therefore find no sense in a definition of Judaism that arrogates that totality. He will instead insist on the obligation of the historian to assemble the facts without imposing on them any grandiose, monolithic scheme. His main concern will remain at the level of empirical phenomena—facts, views, happenings—which he will attempt to analyze in their ordinary operation of cause and effect. He will then readily confess his failure to discover a totality of Jewish phenomena, and will be glad to hand over the material he established to theologians and philosophers for free use by them. But he will be reluctant to attempt to do their job and define Judaism in toto.