What is the Rule of Postponement?
When the Jewish calendar was made public by Hillel II in 358 A.D., it included several new laws or rules called postponements. These laws made it necessary to actually delay Yom Teruah (Day of the Blowing) a/k/a Rosh Hashanah, to keep Yom Kippor (Day of Atonement) from falling on a Friday or a Sunday, and to keep Hoshana Rabbah the seventh day of the Feast of Tabernacles (Booths) or Chag Succote from falling on the weekly Sabbath. This is avoided so that there will not be two days in a row on which it is forbidden to prepare food or do the other sorts of work that are permitted on secular days. Since Yom Kippor is one week and two days after Yom Teruah (Rosh Hashanah), Yom Teruah cannot fall on a Wednesday or a Friday in order that Yom Kippor not fall on a Friday or Sunday. This law/rule also prevents the seventh day of Chag Succote (called Hoshanah Rabbah) from falling on the Sabbath, in which case Jews would not be able to perform a ritual called arava and the seven hakofos. In order
