Maimonides wrote his great code, the Mishneh Torah, without citing the sources of his rulings. An earlier commentary, the Maggid Mishneh, had traced them for only part of the work. In the Kesef Mishneh Karo set out to find the source of every law, to explain the Rambam’s reasoning, and to defend him against the critical glosses of the Raavad (Rabbi Avraham ben David of Posquières).
It was printed in Venice in 1574–1576, in the last years of Karo’s life, and has appeared beside the Mishneh Torah in almost every edition since. Every student who opens a Rambam studies with Karo at his side.
