The last day of Succoth, the Feast of Booths, is commonly called Hoshana Rabbah (the Great Hosanna). The ceremony dates back at least to the Maccabean period, about 165 BC, and is related to a ceremony praying for rain for the following year.
As on the other days of Succoth, the celbrants carry the "four species," the representatives of the types of plants specified in Leviticus 23--myrtle, citron, willow, and palm. They parade around the synagogue seven times (as opposed to the one time on each of the other days of Succoth) quoting Psalm 118:25: "Save now [Hosanna], I beseech thee, O Lord: O Lord, I beseech thee, send now prosperity." The days is called the Great Hosanna because it is repeated seven times, rather than once.
Succoth, and therefore Hoshana Rabbah, always come in the fall, the first day of Succoth coming four days after Yom Kippur. This year (2000) Succoth begins on October 14, and Hoshana Rabbah falls on October 20.
Imagine the surprise of the Jewish leaders, then, when one spring, a week before Passover, the cremony was enacted on the streets of Jerusalem. The crowd was lining one particular street, carpeting the road with palm (and possibly myrtle and willow) branches, and shouting the Hosanna, along with the following verse of Psalm 118: "Blessed be he that cometh in the name of the Lord: we have blessed you out of the house of the Lord." Not only were they celebrating out of season, they were shouting the Hosanna before a young, troublesome Rabbi who was entering Jerusalem on a donkey, and equating him to the messiah. Maybe a few of the teachers even associated this with Zechariah 9:9.
It was strange that the people were celebrating six months out of phase. It was strange, but it was appropriate. It is said that Rosh HaShanna is the Day of Judgement, when God decrees what will happen the following year. After the ten days of repentance, He seals what he has written (and presumably revised) on the Day of Atonement. But he may still change his mind for another ten days. On Hoshana Rabbah, the gates of judgement are closed for the year. In a similar way, Jesus' triumphal entry into Jerusalem was really the closing of the gates to any other path except to the cross. He would pray later "let this cup pass from me." (Matt 26:39) However, the people's reaction in a Great Hosanna on his entry into the city had such an impact on the rulers (Lk 19:47; Jn 12:19) that he could no longer turn back.
The Hoshana Rabbah out of time, though, celebrated not only the sealing of Jesus' path to the cross, but the sealing of the way of salvation for all people for all time.
But now once in the end of the world hath he appeared to put away sin by the sacrifice of himself. And as it is appointed unto men once to die, but after this the judgment: so Christ was once offered to bear the sins of many; and unto them that look for him shall he appear the second time without sin unto salvation. (Heb 9: 26-28)