By Maimonides. This volume includes the laws pertaining to the annual donation of a half-shekel, the establishment of the Jewish calendar and an understanding of the movement of the celestial spheres. The Rambam reveals the methods of calculations used by the Sages to build the Jewish calendar, a deep abstract matter in itself. This volume, a continuation of the Mishneh Torah series, presents a vowelized Hebrew text, a facing translation, illustrative diagrams, and a concentrated, but inclusive commentary.