NAHMAN KROCHMAL (1785–1840), a pioneer of the Wissen schaft des Judentums movement, in which Judaism was studied in terms of its historical development, wrote for this very purpose his Moreh nevukhei hazeman (‘Guide for the Perplexed of the Time’), which was published in Lemberg in 1851, fifteen years after Krochmal's death, by the great Jewish historian Leopold Zunz (1794–1886), the leading figure in the Wissenschaft des Judentums movement. Krochmal's title, obviously based on Maimonides’ Moreh nevukhim (‘Guide of the Perplexed’), means that the work is directed to contemporaries, to intelligent Jews in the first half of the nineteenth century, who were quite different from the perplexed individuals to whom Maimonides offered his guidance. The latter were puzzled by the apparent contradictions between Jewish thought and Aristotelian physics and metaphysics. In the Middle Ages philosophical postulates were treated as if they were timeless, as if they belonged in a metahistorical universe of discourse, which is why Maimonides, for example, saw no incongruity in reading Greek ideas into the ancient biblical texts. Krochmal, on the other hand, was offering guidance to Jews with the particular problem of their time, of the modern age. These men, through their study of Western thought, had come to realize that Judaism, like all other religions, is not static but dynamic, with the implication that ideas suitable to one age were not necessarily to be accepted in the same way or at all in a different age. As Zunz once put it, the Jewish Middle Ages only came to an end at the time of the French Revolution, Jews having been precipitated into modernity to face problems with which Western thinkers had been grap pling for centuries. Krochmal's is probably the most acute philosophical treatment of this basically new approach, although both Krochmal and Zunz acknowledged that the historical critical school owed much to the Italian scholar Azariah dei Rossi (c.1511–c.1578), the trailblazer in the attempt to discover what actually happened in the past, even if the discoveries ran counter to passages in the Talmud.

Krochmal's introduction, after stating that God in His wisdom has created each age with its own particular way of understanding and interpreting eternal truths, cites Psalm 137 (‘By the rivers of Babylon’) as an illustration of how this philosophy works.