Commentaries:
This seventh holy day is observed immediately following the Feast of Tabernacles. Biblically, seven symbolizes perfection. It is also the eighth day of the Feast, and the Hebrew word for "eight" is related to another meaning "fatness," implying abundance, fertility - even resurrection and regeneration. According to Jewish tradition, on the Last Great Day, they finished reading what they started when Tabernacles began. Though intimately connected to the Feast of Tabernacles, it holds a distinct meaning of its own. It is part of it yet separate.
The offerings required on this day in the Old Testament were the largest of all, typifying Israel's thankfulness to God for all He provided. Today, God's people keep this day with praise and thankfulness - spiritual sacrifices (Hebrews 13:15) - for His abundant spiritual gifts.
Martin G. Collins
Holy Days: Last Great Day