Created according to the ancient Israelite festivals related to the harvest. This calendar is different from the rabbinic calendar, the Karaites' calendar of today and the Qumran calendar. It is in accordance with the ancient rules of the feasts and appointments of the Lord according to the lunisolar cycle of the Jewish almanacs of antiquity.
"The entire system of Judaism was the gospel. True, it was veiled in types and symbols, but the light from Calvary illuminates the entire Jewish economy; and the one who will study it in the light of the cross, will gain such an intimate acquaintance with Him who is the Antitype of every service, that by beholding they will become changed into His image, from glory to glory.
The typical service shines the brightest when placed by the side of the Antitype. A study of any part of the Levitical system points to some characteristic in the life of Christ; while a study of the entire system of Judaism more nearly reveals the fullness of His character than any other portions of the Scriptures. The entire Bible is full of it.
Every Bible writer refers to the Levitical service to illustrate divine truth; and the person who is familiar with the entire sanctuary service, not only, receives a blessing from the study, but also understands more fully other portions of the Sacred Book, for the different feasts and sacrifices are referred to frequently all through the Bible."
Haskell, Stephen Nelson (Adventist Pioneer Library).