Gershom was the first commentator of the vast Talmud, and he who knows the difficulty of such a work will appreciate how much energy, devotion, and patience were required for it. He was at once recognized as an authority by the German, French, and Italian communities. Questions were submitted to him, and unwittingly he became the rival of the last Gaon Haï, although he looked upon him with the reverence of a disciple. Through a peculiar combination of circumstances those who respected the Gaonate most, contributed to its decay. Gershom's commentaries on the Talmud, written in Hebrew, had the result that the Gaonic school could be dispensed with, and thus severed the German communities and those of northern France from it. Any one who chose to do so could obtain a deep knowledge of the Talmud without first seeking aid from Babylonia. Gershom also busied himself with the Massora, and made a place for its study, which until then had been pursued only in Mahometan countries, in Germany and in France. Gershom became even more famous through his decrees than through his commentaries. They produced a very wholesome effect upon German and French Judaism. Amongst other things he forbade polygamy, practiced even among European Jews, allowing it in extreme cases only. He decreed further that the consent of the wife was necessary for a divorce, whilst, according to the Talmud, the husband could give her a bill of divorce against her wish. He also made an important rule about the carrying of letters, viz., that the bearer must not read a letter, even though it be not sealed. In those times intercourse with one's friends was carried on by means of travelers who happened to be going in the direction required. Hence this regulation was of the utmost importance. Those who transgressed this decree were to be laid under the ban of excommunication. Although these and other institutions were without synodal formality, and the author of them was in no way invested with official authority, yet, so great was the respect felt for Gershom, that they were received by the German and French communities like the decrees of a synhedrion, and scrupulously obeyed. Contemporary with this authority of the German-French communities, there lived in Mayence a man whose merits were, until recently, unappreciated. This man was Simon ben Isaac ben Abun, of French descent, from Le Mans. He was learned in the Talmud, and wrote an original work (Yessod) on it. He was, besides, a versatile and prolific Hebrew poet (Poetan), and wrote a number of liturgical compositions in the style of Kaliri, as heavy and ungraceful as his, in which he introduced the Agadic literature, often in an enigmatical way. Simon ben Isaac was wealthy, and was thus able to avert the storm which had gathered, and was threatening to break over the Jews of Germany.