IGGERET HA-KODESH (Heb. אִגֶּרֶת הַקֹּדֶשׁ; "Holy Epistle"), an anonymous 13th-century kabbalistic work, since the 14thcentury usually but wrongly attributed to *Nahmanides. It has been suggested that the author might be R. Joseph b. Abraham *Gikatilla, the friend and associate of R. *Moses b. Shem Tov de Leon, author of the *Zohar, but this has yet to be proven. In the selection and treatment of the subject the work is unusual among the writings of the early kabbalists. Whereas the early kabbalists wrote their popular ethical books in a manner which attempted to conceal their kabbalistic ideology, Iggeret ha-Kodesh is primarily an ethical work written with its kabbalistic ideas in full view. It may be said that this is the first popular work in which kabbalistic teachings are applied to everyday behavior. It was not until three centuries later, in 16th-century *Safed, that such applications were made on a large scale (see *Ethical Literature). The book's six chapters deal with the problems of leading a moral family life, giving particular emphasis to the way in which a pious Jew should conduct sexual intercourse with his wife. The hygiene and sanctity of sexual life are discussed in great detail. To a large degree the work is an anthology of quotations and interpretations of talmudic and midrashic sayings about sexual relations. The work may be regarded, moreover, as a polemical answer to both Aristotle and Maimonides who regarded sexual activity as being a lower, because less spiritual, level of life. The author of Iggeret ha-Kodesh upholds the sanctity of sexual relations provided, of course, that it is conducted strictly in accordance with rabbinic laws and instructions. The author's major thesis is that human sexual intercourse is a reflection of the mystical union in kabbalistic writings between two of the divine Sefirot (see *Kabbalah): Tiferet, the symbol for the husband in the heavenly world, and the *Shekhinah, the symbol for the wife. Thus, there is a mystical significance to human sexual behavior whereby proper sexual relations between man and wife in this world contribute to the achievement of unity in the divine world.
Iggeret ha-Kodesh was often quoted in late 13th- and early 14th-century kabbalistic literature, and many ethical writers included it either whole or in part in their own books. Among those who thus borrowed from the work were R. Meir b. Isaac *Aldabi in Shevilei Emunah (Riva, 1558), R. Elijah b. Moses de *Vidas in Reshit Hokhmah, and Israel b. Joseph *Al-Nakawa, who included the whole treatise in his ethical anthology Menorat ha-Ma'or, 4 vols. (1929–32). Many manuscripts of the work, some quite old, and many printings (the first, Rome, 1546), are extant.
C.B. Chavel, Kitvei Rabbenu Moshe ben Naḥhman, 2 (1963), 315–37.