Shulchan Aruch

Karo kept the four-part structure that Jacob ben Asher had devised for the Arba'ah Turim two centuries earlier, and the divisions have organised practical halakhah ever since. Orach Chayim, the Way of Life, follows the daily and yearly round: waking, prayer, blessings, Sabbath and the festivals, the laws a Jew meets every single day.

Yoreh De'ah, It Shall Teach Knowledge, gathers the ritual law that requires learned decision, including the dietary laws of slaughter and mixtures, idolatry, vows, circumcision, conversion, mourning and the honour due to Torah scholars. Even ha-Ezer, the Stone of Help, covers marriage, divorce and the marriage contract. Choshen Mishpat, the Breastplate of Judgment, holds civil and judicial law: courts, testimony, loans, partnership, damages and inheritance.

Within each section the chapters, simanim, are numbered continuously and subdivided into paragraphs, seifim, so that any ruling can be cited in a few characters. The work's genius was compression. Karo had already written the Beit Yosef, an exhaustive survey of every opinion from the Talmud onward, keyed to the Tur; the Shulchan Aruch states only his conclusions, in short declarative Hebrew, a table set with decisions rather than deliberations, intended, as he wrote, to be reviewed regularly until its rulings were fluent.

The Shulchan Aruch nearly divided the Jewish world it ended up uniting. Karo, an exile from Spain writing in the kabbalistic centre of Safed, decided the law by majority vote among his three pillars, Alfasi, Maimonides and Asher ben Yechiel. Two of the three were Sephardic authorities, and the resulting code often ruled against the customs of Ashkenaz.

In Krakow, Rabbi Moses Isserles, the Rema, had been preparing a code of his own; on seeing Karo's work he chose annotation over rivalry. His glosses, printed in the text in a different typeface from the 1570s onward, record wherever Ashkenazic practice differs, invoking the principle that established custom has the force of law. He called them the Mapah, the Tablecloth spread over Karo's Set Table, and the shared metaphor was apt: one table now served two worlds, with Sephardic and Mizrahi communities generally following Karo's plain text and Ashkenazic communities following the Rema's gloss. Around this joint text grew rings of standard commentaries, the Shakh and Taz on Yoreh De'ah, the Magen Avraham on Orach Chayim and many others, and later restatements such as the Mishnah Berurah track its chapter numbers. To rule from within its frame remains the ordinary meaning of deciding Jewish law.