Custom becomes law: Ashkenaz writes itself down

In a hundred and twenty years German Jewry turned its "this is how we do it" into written law.

Custom is an oral thing. It lives by having been seen: how grandfather led the seder, how this synagogue sang Kol Nidrei, what was not done in the Nine Days. While a community stays put there is no reason to write it down.

In fifteenth-century Ashkenaz there came to be a reason. Communities were driven from place to place—the Hussite wars, exactions, expulsions from one town after another; people went east into Poland carrying their custom with them, and there it had to be backed by something. And so, generation by generation, they began to write it down.

The Maharil, the foremost man of Germany, Austria and Bohemia in his time, wrote no books at all—a student, Rabbi Zalman of St. Goar, recorded him, and the Sefer Maharil came out: not a code but the round of the year and the occasions of life, down to how they stood and how they sang. Rabbi Israel Isserlein at Wiener Neustadt went the other way: he posed himself the questions and worked them through—the 354 sections of Terumat ha-Deshen, a subject taken whole. Rabbi Jacob Weil, the Maharil's student, wrote the rules of slaughter and inspection, and from them the Ashkenazi slaughterer learned his craft through seventy-one editions. Rabbi Israel Bruna at Regensburg answered the letters of all Germany—and left the fullest portrait of its daily life.

A century and a half later Rabbi Moses Isserles at Krakow will write the Mapah—the glosses on Rabbi Joseph Karo's Shulchan Aruch that turn a Sephardi code into a common one. He will have to take Ashkenazi custom from books, and he will take it from here: nearly everything he says about custom comes from the Maharil and Isserlein.

So 'this is how we do it' became 'thus it is ruled'.