32 On that day the night decreases and amounts to nine parts, and the day to nine parts, and the night is equal to the day and the year is exactly as to its days THREE HUNDRED AND SIXTY-FOUR. 33. And the length of the day and of the night, and the shortness of the day and of the night arise–through the course of the sun these distinctions are made.
With this calendar the year always contains precisely 364 days. Each year consists of twelve months of thirty days each, plus four additional days, one of which is intercalated at the end of each three-month period. Thus the first and second months are 30 days long, while the third month totals 31 days; then the pattern repeats. New Year’s Day and the first day of each three-month period always fall on a Wednesday.
Wednesday is the day mandated as the first day by the creation order, since the heavenly lights – sun, moon and stars, the basis of any calendar – were created on the fourth day (Gen. 1:14-19). The great advantage of the Zadok calendar over its lunisolar rival is that it results in fixed dates for the major festivals.
They cannot fall on a Sabbath, thereby avoiding worrisome difficulties affecting sacrifices. In fact, this calendar guarantees that a particular day of any given month will always fall on the same day of the week every year.
Since the solar calendar totaled 364 days to the year and the lunisolar calendar alternated months of 29 and 30 days, the lunisolar calendar would ‘fall behind’ by ten days per year, which is exactly what Jubilees warns us about. After three years, the lunisolar calendar required intercalation with an additional 29 or 30 days, bringing the two versions once again into harmony (364 X 3 = 354 X 3 + 30). Without the intercalation of the lunisolar calendar, the Feasts would not be observed in their seasons as commanded by Yah. This is not a problem with the Zadok calendar since it is based upon the vernal equinox.
And all the children of Israel will forget and will not find the path of the years, and will forget the Months, and Seasons, and Sabbaths and they will go wrong as to all the order of the years. For I know and from henceforth will I declare it unto thee, and it is not of my own devising; for the book (lies) written before me, and on the heavenly tablets the division of days is ordained, lest they forget the feasts of the covenant and walk according to the feasts of the Gentiles after their error and after their ignorance. For there will be those who will assuredly “MAKE OBSERVATIONS OF THE MOON −how (it) DISTURBS THE SEASONS and comes in from year to year TEN DAYS TOO SOON.
For this reason the years will come upon them when they will Disturb (the order), and make an Abominable (Day) the Day of Testimony, and an Unclean Day a Feast Day, and they will confound all the days, the holy with the unclean, and the unclean day with the holy; for THEY WILL GO WRONG AS TO THE MONTHS AND SABBATHS AND FEASTS AND JUBILEES. For this reason I command and testify to thee that thou mayst testify to them; for after thy death thy children will disturb (them), so that THEY WILL NOT MAKE THE YEAR THREE HUNDRED AND SIXTY−FOUR DAYS ONLY, and for this reason they will go Wrong as to the Months and Seasons and Sabbaths and Festivals, and they will eat all kinds of blood with all kinds of flesh.
Zadok Priestly Order
The calendars found in the Qumran scrolls were reckoned not only by months, but also by the rotation of the priestly courses (mishmarot).
The courses would come into Jerusalem for service at the temple for one week, then rotate out as the next group arrived to serve. Qumran texts relied upon this ‘eternal cycle’ not only for their calendar, but also for their chronology and history. Every Sabbath, month, year and feast bore the name of a priestly family.
The priestly rotation required six years before the same group would be serving once again in the same week of the year. The order of the priestly courses was originally determined by lot, and is laid out in 1 Chr. 24:7-18 as follows: