Rabbi Isaac Israeli was a Jewish astronomer in Toledo. He authored the Yesod Olam in 1310, with the basic rules of the Jewish calendar. At the time, Yesod Olam was the most important work on this subject in Hebrew and many relied on it over the next hundreds of years. The work was first printed in Berlin in 1777, about twenty years after this manuscript was copied.
” Sefer Yesod Olam authored by Yitzchak HaYisraeli, disciple of Rabbeinu Asher z”l on the laws of sanctifying the month … and the tekufuot and mazalot …”
The copier only copied article 1, chapter II, shaar 1. With some minor changes from the printed version and many more sketches than in print (Berlin, 1848).
With comments, commentaries and glosses, some marginal and some interlinear.
Two supplements at the end of the book. The first (105a-105b) “Yitzchak son of Yisrael said a story that happened in Sivan … that … claimed that the Jews ate chametz on the first and second day of Pesach … and they could not respond … and asked me to respond for them … and right when I received this manuscript I saw that there was no basis … and I went over to them and I nullified it with true proofs.” The second section features charts for predicting the Moladot of the moon and the planets, but only some are filled in. These charts belong to Isaac Israeli’s Shaar HaShamayim , with charts 50-53 of the printed version.
The colophon states: “Copied by Yaakov Zev son of Shlomo Zalman … on Friday, the 8th of Elul, 1755.”
119 leaves. 31 cm. Nice Ashkenazic hand. Illustrated title page. Decorative leaf, flower or fruit at the start of each chapter. Picture of a deer at the end of the work. Provenance: Bill Gross Collection 225. Fine condition. Aging stains. Restored blemishes on the title page. Deluxe leather binding.