נתן בן יחיאל מרומי

Rabbeinu Nathan ben Yechiel of Rome (c. 4795/1035–1106), known simply as the Aruch after his sefer and in English sources as Nathan ben Jehiel, was a chacham, posek and rosh yeshiva of Rome in the days of the rishonim. He was born into one of the four distinguished families of Rome that the mesorah says Titus brought there from Yerushalayim at the churban of the second Beit HaMikdash. His father, Rav Yechiel bar Avraham Gaon, was a famous rav in Rome and an accepted authority in halacha. The Roman community placed the presidency of its rabbinic college in the hands of Rav Yechiel’s three sons — Daniel, Avraham and Nathan — so that they were styled the geonim of the house of Rav Yechiel, and questions came to them from many lands, among them three from Mar Shlomo HaYitzchaki, whom many identify with Rashi.

He did not begin as a lamdan but as a peddler of linen, and the death of the man he worked for turned him from trade to Torah. He learned by his father, and in Italy by Rav Moshe Kalfo of Bari and by Rav Matzliach the dayan, a chacham of Sicily who had learned in Bavel by Rav Hai Gaon, the last of the geonim of Pumbedita. He learned as well in the yeshiva of Narbonne by the baal aggadah Rav Moshe HaDarshan. He appears to have been a man of means, building a splendid shul together with his brothers in 4862/1102. Of his five sons, four were niftar in his lifetime and only Reuven remained, and he mourned them in a poem appended to his great work.

The Aruch, which he completed in 4861/1101, is a dictionary of the difficult words of the two Talmuds and the midrashim, leaning above all on the writings of the Geonim and of the earliest rishonim — Rabbeinu Chananel, Rabbeinu Gershom Me’or HaGolah — and at times on his own explanation. Every entry carries a full explanation that takes in the matters bound up with the word, so that the sefer is a collection not only of words but of subjects in the literature of chazal. The citations of Rabbeinu Chananel are so thick in it that Rabbeinu Tam held the work to rest entirely on his commentaries.

It is the earliest comprehensive dictionary of the literature of chazal, and every later rabbinic lexicon was built on it; rishonim quote it in explaining the Gemara and the midrashim. Several works — among them Tanna d’Vei Eliyahu and Avot d’Rabbi Nathan — are first called by name in it. Supplements gathered round it, among them the Musaf he-Aruch of Rav Binyamin Musafia. The sefer was first printed in Italy around 5230/1470, among the earliest Hebrew books ever printed, and Daniel Bomberg of Venice issued it in 5291/1531.