Rabbi Jacob Emden — Yaavetz רבי יעקב עמדין — היעב"ץ

Born at Altona on 4 June 1697, died there on 19 April 1776. From 1710 to 1714, as a boy and adolescent, he lived at Amsterdam studying with his father — so the Hayyun affair passed before his eyes and shaped him for life. He then studied at Ungarisch-Brod, was rabbi of Emden in 1728–33, and thereafter lived in Altona, refusing salaried rabbinic office and living as a jeweller, printer and scholar. In 1751 he was briefly in Amsterdam again, a refugee at the height of the Eybeschütz war.

From the Danish crown he obtained the right to a private synagogue and a Hebrew press (the sources differ: 1743 or 1745). His siddur Beit Ya'akov (Altona, 1745–48) is one of the most important prayer-book editions ever made and is still consulted.

The quarrel with R. Jonathan Eybeschütz began in 1751, when Eybeschütz took the post of the three communities that Emden's father had once held. Emden read hidden Sabbatean formulae in Eybeschütz's protective amulets. The dispute drew in the Council of Four Lands, the rabbis of Poland, the Hamburg senate and the Danish crown; in May 1751 the local council declared Emden a slanderer and he fled to Amsterdam, where his brother-in-law R. Aryeh Leib ben Saul Löwenstam, Ashkenazi chief rabbi of Amsterdam, supported him. He returned in 1752 after the Danish king intervened.

The most unexpected thing about him is Mitpahat Sefarim (Altona, 1768): by philological argument he showed that substantial parts of the Zohar cannot go back to the time of R. Shimon bar Yohai and must be medieval. He did it as a defender of tradition — to take the Zohar out of Sabbatean hands — but the method is that of later critical scholarship, and maskilim and Wissenschaft scholars cited him constantly. In Resen Mat'eh, appended to his edition of Seder Olam (1757), stands his celebrated positive assessment of Christianity and Islam as legitimate faiths for the nations, founded by men who came to spread the Noahide laws.

Two corrections. He did not "prove" Eybeschütz a Sabbatean: the case remains disputed, most contemporary rabbis sided with Eybeschütz, and the amulet readings rest on contested decipherments — though Eybeschütz's son Wolf later behaved as an open Sabbatean. And the stock image of an obscurantist is a Haskalah-era caricature that reached Russian literature through Graetz: a man who disputed the antiquity of the Zohar, wrote an autobiography of modern candour and praised the civilising work of Christianity was a critic inside tradition.