Yahrtzeit of Rabbi Yaakov Ben Asher (1268-1340), author of the seminal book of Jewish law, The Tur. This was a groundbreaking contribution to Jewish scholarship in that it organized all practical Jewish law into four major sections, subdivided into hundreds of chapter headings. This system served as the foundation for all later rabbinic works, including Rabbi Yosef Karo's Shulchan Aruch, the standard Code of Jewish Law. Rabbi Yaakov lived in Spain and was the son of the famous talmudic commentator, the Rosh. He lived in abject poverty most of his life. Rabbi Yaakov also wrote a commentary on the Five Books of Moses, entitled Ba'al HaTurim, which focuses on hidden messages in the Torah -- gematria (numerology), acrostics and word patterns.