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Mosheh ben Aharon ha-Kohen of Kraków

(Johan Kemper; d. 1716), Sabbatian kabbalist; after his conversion to Christianity, lector in Hebrew at the University of Uppsala. Little is known about Mosheh ben Aharon’s early activity. It is certain that he was active in one of the groups linked to Yehudah Ḥasid, which around 1695 began to prepare to immigrate to Palestine in order to await Shabetai Tsevi’s second coming in Jerusalem.

Mosheh ben Aharon was attracted to the preaching of the Sabbatian prophet Tsadok ben Shemaryah of Grodno, a former brandy distiller who appeared around 1694, traveled through Eastern and Central Europe, and foretold redemption in the year 1695. Following the failure of this prophecy, Mosheh became receptive to the Christian message that Sabbatian expectations should be abandoned because the messiah had already come.

It seems that even before his conversion, Mosheh ben Aharon had had some contacts with Christian scholars, notably with orientalists Johann Christian Wagenseil and Laurentius Normannus. Toward the end of 1696, he converted to the Augsburg Confession in Schweinfurt and accepted the name of Johan Christian Jakob Kemper. In the same year, he published an account of his baptism and of the movement surrounding Tsadok of Grodno, and started teaching Hebrew at a German university, most likely in Altdorf. The following year he moved to Sweden and taught Hebrew and rabbinics at Uppsala, where he remained until his death.

During his tenure at Uppsala, Kemper wrote his major works, most notably a three-volume commentary on the Zohar titled Mateh Mosheh and a kabbalistic commentary on the Gospels, “Me’irat ‘enayim” (unpublished manuscript). He also embarked on a project of translating the Gospels into Hebrew, although only a translation of Matthew was completed.

The prime aim of Kemper’s works was to demonstrate the truth of Christianity on the basis of Jewish sources. Although the main focus is on kabbalistic speculation, his work is unusual in its attempt to find Christian elements in halakhah as well, and in the observance of traditional Jewish customs and rituals. According to Kemper, the truth of Christianity can be fully appreciated against its Jewish background. Thus he holds that the entire Jewish tradition contains intimations of Christianity that are impenetrable to the majority of Jews.

Kemper sought both to make kabbalistic speculation available to Gospel scholars and to convince Jews of the truth of Christianity. Unstated Sabbatian motifs (such as the doctrine of the tripartite division of the godhead) served for him as a bridge between the two religions. His translation of the Gospels from Syriac was intended as a missionary aid but contains many heretical Jewish elements that deviate from Christian doctrine. Similarly, his Hebrew commentary to Matthew (translated into Latin by Anders Norrelius) contains many Sabbatian doctrines that were most likely not recognizable as such to his Christian readers.

Suggested Reading

Shifra Asulin, “Another Glance at Sabbatianism, Conversion, and Hebraism in 17th-century Europe: Scrutinizing the Character of Johan Kempper of Uppsala, or Moshe Son of Aharon of Krakow,” in Ha-Ḥalom ve-shivro, ed. Rachel Elior, vol. 2, pp. 423–470 (Jerusalem, 2001); Hans-Joachim Schoeps, Philosemitismus im Barock (Tübingen, 1952), pp. 92–133; Hans-Joachim Schoeps, Barocke Juden, Christen, Judenchristen (Bern, 1965), pp. 60–67; Elliot Wolfson, “Messianism in the Christian Kabbalah of Johann Kemper,” in Millenarianism and Messianism in Early Modern European Culture, ed. Matt Goldish and Richard Popkin, pp. 139–187 (Dordrecht, Neth., 2001).