Jacob ben Asher
The author of the Arbaah Turim set the scene for the publication of Karo's Shulhan Arukh.
Jacob ben Asher was a German Halakhist (d. 1340), the son of Asher ben Jehiel, the outstanding authority in German and later Spanish Jewry, known as the Rosh (after the initial letters of his name, Rabbi Asher).
Under threat of persecution, Jacob with his father left Germany for Spain in 1303. The Rosh became Rabbi of Toledo but Jacob refused to take up a Rabbinic appointment and lived a life of poverty, only partly relieved by money he received from time to time from patrons of learning.
Jacob is chiefly renowned for his great Code of Jewish law (first published in Piove di Sacco in 1475 and thus one of the very earliest Jewish works to be printed), known as Arbaah Turim ('Four Rows').
The name is based on the four rows of precious stones in the breastplate of the High Priest (Exodus 28:17), usually abbreviated to Tur, so that in Halakhic literature both Jacob himself and his Code are called 'the Tur'.
The work consists of four sections, hence the 'four rows'. These are:
1. Orah Hayyim; 'Path of Life' (after Psalms 16:11), dealing with prayer, the Sabbath and festivals, and with general religious duties
2. Yoreh Deah, 'Teaching Knowledge' (after Isaiah 28:9), dealing with the dietary laws and other topics required chiefly for Rabbinic decisions on more complex matters
3. Even Ha-Ezer, 'Stone of Help' (after I Samuel 5:1 and Genesis 2:20, where woman is the 'help' meet for man), dealing with the laws of marriage and divorce
4. Hoshen Mishpat, 'Breastplate ofJudgement' (after Exodus 28:15), dealing with civil law and jurisprudence in general
The Tur quickly took its place beside the Codes of Isaac Alfasi and that of Maimonides as a major textbook of Jewish law.
Father & Son
Jacob uses as his sources the two Codes which preceded him, other Halakhic works produced by both Sephardim and Ashkenazim, and, especially, the rulings of his father, the Rosh, all of whom he treats with great deference while often pursuing a line of his own, disagreeing, on occasion, even with his father.
In the introduction to the 'Laws of the Sabbath' Jacob remarks, in a revealing aside, that he had discussed many times with his father, the Rosh, whether someone in a similar situation to his, who has to rely for his support on charitable donations, is obliged to spend money on extra food and drink for the Sabbath meals.
The father's replies were far from clear, he observes, and he had to make up his own mind. Later authorities relied on the Tur's disagreement with the Rosh to demonstrate that the fifth commandment does not mean that a son is duty-bound to agree with his father's opinions in matters of Torah learning.
Rabbi Joseph Karo compiled his Bet Yosef (house of Joseph), as a commentary on the Tur and the Bet Yosef formed in turn the basis of Karo's own Code, the Shulhan Arukh.