I noticed that the Sefer HaChinukh (§4) attributes the calendar to Rabbi Hillel II, whom the mechaber says was the son of Rabbi Yehudah HaNasi. I have never before encountered the idea that Rabbi Hillel II was Rabbi Yehudah HaNasi’s son. Is this idea widespread? Are there others who think that the calendar was produced that early?

  • 3
    He probably meant Rabbi Yehudah Nesi'ah, whose title translates as Ha'nasi. As it turns out, according to Wikipedia, there's a debate whether he was the son of Rabbi Yehudah Nesi'ah I or Rabbi Yehudah Nesi'ah II (also known as Rabbi Yehudah Nesi'ah III).
    – Harel13
    Commented May 6, 2023 at 18:41
  • judaism.stackexchange.com/questions/45700/…
    – Double AA
    Commented Jun 30, 2023 at 19:15

1 Answer 1


The earliest written reference to the name Hillel is found in a responsum by R. Hai Gaon. It mentions Hillel b. Yehuda, who established the fixed calendar in 358/9 CE, about 140 years before the completion of the Talmud. However, beyond R. Hai's account, there is no other information about a "Hillel b. Yehuda" from Jewish sources in the 4th century. Later commentators assume that Hillel belonged to the Nesi'im dynasty and was a patriarch, following the lineage of Hillel the Elder. Some inaccurately suggest that Hillel was the son or grandson of R. Yehuda HaNasi, likely due to copying errors. The commonly accepted view identifies Hillel as the great-grandson of R. Yehuda HaNasi, but this creates historical difficulties as there were multiple individuals named "R. Yehuda Nesiah" descended from Rabbeinu HaKadosh. It is more likely that the Hillel mentioned by R. Hai Gaon was the son of R. Yehuda III Nesi'ah, Rabbeinu HaKadosh's great-great-grandson.

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