This Sefer ha-mizvot was executed as a preparation for his principal work, the Mishneh Torah, or Yad ha-hazakah, which consists of an Introduction and fourteen Books. In the Introduction the author first describes the chain of tradition from Moses to the close of the Talmud, and then he explains his method in compiling the work. He distinguishes between the dicta found in the Talmud, Sifre, Sifra, or Tosefta, on the one hand, and the dicta of the Geonim on the other; the former were binding on all Jews, the latter only as far as their necessity and their utility or the authority of their propounders was recognized. Having once for all stated the sources from which he compiled his work, he did not deem it necessary to name in each case the authority for his opinion or the particular passage from which he derived his dictum. Any addition of references to each paragraph he probably considered useless to the uninformed and superfluous to the learned. At a later time he discovered his error, he being himself unable to find again the sources of some of his decisions. Rabbi Joseph Caro, in his commentary on the Mishneh Torah, termed Keseph Mishneh, remedied this deficiency. The Introduction is followed by the enumeration of the six hundred and thirteen precepts and a description of the plan of the work, its division into fourteen books, and the division of the latter into sections, chapters, and paragraphs.
According to the author, the Mishneh Torah is a mere compendium of the Talmud; but he found sufficient opportunities to display his real genius, his philosophical mind, and his ethical doctrines. For in stating what the traditional Law enjoined he had to exercise his own judgment, and to decide whether a certain dictum was meant to be taken literally or figuratively whether it was the final decision of a majority or the rejected opinion of a minority; whether it was part of the Oral Law or a precept founded on the scientific views of a particular author; and whether it was of universal application or was only intended for a special period or a special locality. The first Book, Sefer ha-madda', is the embodiment of his own ethical and theological theories, although he frequently refers to the Sayings of our Sages, and employs the phraseology of the Talmud. Similarly, the section on the Jewish Calendar, Hilkot ha-'ibur, may be considered as his original work. In each group of the halakot, its source, a certain passage of the Pentateuch, is first quoted, with its traditional interpretation, and then the detailed rules follow in systematic order. The Mishneh Torah was written by the author in pure Hebrew; when subsequently a friend asked him to translate it into Arabic, he said he would prefer to have his Arabic writings translated into Hebrew instead of the reverse. The style is an imitation of the Mishnah he did not choose, the author says, the philosophical style, because that would be unintelligible to the common reader; nor did he select the prophetic style, because that would not harmonize with the subject.
Ten years of hard work by day and by night were spent in the compilation of this code, which had originally been undertaken for "his own benefit, to save him in his advanced age the trouble and the necessity of consulting the Talmud on every occasion." Maimonides knew very well that his work would meet with the opposition of those whose ignorance it would expose, also of those who were incapable of comprehending it, and of those who were inclined to condemn every deviation from their own preconceived notions. But
