Rav Achai of Shabcha רב אחאי משבחא

Between the sealing of the Talmud and the first written book lie four centuries in which nothing was composed: the Geonim answered the questions of communities, and the answers went out as letters. The Sheiltot of Rav Achai breaks that order—it is the first book of the post-Talmudic age to reach us whole.

Its arrangement is unusual: for each weekly portion a "sheilta", a question beginning from a commandment in that portion; then an analysis from the Talmud, then a homily, then a ruling. The law is presented not as a list but as a discourse tied to what the congregation is reading that Sabbath anyway. Many would repeat the device afterwards—from the Sefer haChinuch to today's weekly sheets.

Of Rav Achai himself little is known: he was from Shabcha in Babylonia, a man of vast learning, but never became Gaon—by tradition the post went to his own student—and he left for the Land of Israel. His book was written about the year 4510 and is cited by all the Rishonim.

The years are taken from the Epistle of Rav Sherira Gaon—the letter of 4747 (987), the only source in which the age of the Savoraim is set out by name and year. There is no other testimony, and that should be kept in mind.