We all know the words of the Psalmist, “The Lord preserveth the simple.” But as there are periods in the life of the individual when naïveté has to give way to sagacity and reflection, so there are times in history at which Providence does not choose to leave men in simplicity. At such times doubts arise, as though of themselves; questions suddenly become open when they had been supposed solved for centuries; and the human mind is stirred by a sceptical breeze of which no man can tell whence it came. One may under those circumstances be indifferent, but one can be simple no more. Even in such cases, however, man has no cause to despair. When our dearest beliefs are shaken by all kinds of doubts, Providence sends us also great thinkers, earnest lovers of truth, who devote their lives to enlightening our puzzled minds. Not that these men try to answer all the questions by which we feel perplexed. They endeavour to satisfy us, partly by showing that many of our difficulties are not difficulties at all, but merely arise from superficiality, and partly by proving that the great cause about which we feel so much anxiety does not exactly depend on the solution of the questions that are troubling us. They give to the things which are dearer to us than our life a fresh aspect, which enables us to remain attached to them with the same devotion and love as before. To speak again in the words of the Psalmist: “Thou sendest forth Thy Spirit, and they are created, and Thou renewest the face of the earth.” This spirit that renews the face of things is what I understand by “saving knowledge.” As men of that saving knowledge we may regard Rabban Johanan ben Zaccai(19) and his disciples, who made it possible for Judaism to survive the destruction of the Temple, which some believed to involve the end of the religion. As such men we may look upon R. Saadiah Gaon and his followers, who worked at a time when Judaism was menaced in its inner life, namely in the tradition, by the attempts of the narrow‐minded Caraites to convert it into a bookish religion.(20) Such men were Maimonides and his successors, who came to the aid of religion when it had got into dogmatic troubles by reason of its coming into contact with various philosophical systems. And in order to approach the subject of the present essay, I venture to say that a man of such saving knowledge was also Nachman Krochmal, who lived and laboured in the first half of the present century, when Judaism had been terribly shaken by the scepticism of Voltaire, and the platitudes of the so‐called Mendelssohnian school.