Isaiah or Yeshayahu ben Avraham Ha-Levi Horowitz (), (c. 1555 – March 24, 1630), also known as the Shelah HaKaddosh ( "the holy Shelah") after the title of his best-known work, was a prominent rabbi and mystic. Biography Isaiah Horowitz was born in Prague around 1555. His first teacher was his father, Avraham ben Shabtai Sheftel Horowitz, a notable scholar and author, and a disciple of Moses Isserles (Rema). Horowitz studied under Meir Lublin and Joshua Falk. He married Chaya, daughter of Abraham Moul, of Vienna, and was a wealthy and active philanthropist, supporting Torah study, especially in Jerusalem. In 1590, in Lublin, he participated in a meeting of the Council of Four Lands, and his signature appears on a decree that condemns the purchase of rabbinic positions. In 1602, Isaiah Horowitz was appointed Av Beit Din in Austria, and in 1606 was appointed Rabbi of Frankfurt. In 1614, after serving as rabbi in prominent cities in Europe, he left following the Fettmilch Uprising and assumed the prestigious position of chief rabbi of Prague. In 1621, after the death of his wife, he moved to Israel, was appointed rabbi of the Ashkenazi community in Jerusalem, and married Hava, daughter of Eleazer. In 1625, he was kidnapped and imprisoned, together with 15 other Jewish rabbis and scholars, by the Pasha (Ibn Faruh) and held for ransom. After 1626, Horowitz moved to Safed, erstwhile home of Kabbalah, and later died in Tiberias on March 24, 1630 (Nisan 11, 5390 on the Hebrew calendar). In his many kabbalistic, homiletic and halachic works, he stressed the joy in every action, and how one should convert the evil inclination into good, two concepts that influenced Jewish thought through to the eighteenth-century, and greatly influenced the development of Hasidic Judaism. Famous descendants of Isaiah Horowitz included Yaakov Yitzchak of Lublin (known as "The Seer of Lublin"), the prominent Billiczer rabbinical family of Szerencs, Hungary and the Dym family of rabbis and communal leaders in Galicia, Aaron HaLevi ben Moses of Staroselye (a prominent student of Shneur Zalman of Liadi), the Fruchter-Langer families and Rabbi Meir Zelig Mann of Memel, Lithuania (b. 1921, d. 2008). Works His most important work Shenei Luḥot HaBerit (, Two Tablets of the Covenant, abbreviated Shelah ), is an encyclopedic compilation of ritual, ethics, and mysticism. It was originally intended as an ethical will - written as a compendium of the Jewish