The Septenary 364-day Biblical Year

"More than any astronomical aspect, the 364-day year is characterized by its numerical harmony. In fact, the best definition for the year is neither a 'solar' nor 'luni-solar' year but rather a seven-based (septenary) schematic year. This definition gives the best account for most manifestations of this sectarian reckoning. " - Jonathan Ben-Dov 

The 364-Day Year: General Characteristics

More than just encompassing the astronomical aspects of the sun and the moon, the 364-day Calendar retrieved in Qumran is neither ‘solar’ nor  ‘lunar’. This calendar is instead uniquely defined as a "septenary calendar", because of its numerical harmony of the 7-day creation week with the heavenly motions. With the arithmetical and schematic dimensions of the week of Genesis as its first rule while, the 364-day calendrical year is not just a mere mathematical calendar, for it also unites the cycles of the celestial bodies using a seven-based (septenary) schematic cycle. While the observation and calculation of the heavenly motions remain an integral part of the Original Calendar, its 364-day year does not accept any preference for a particular luminary over another, but rather harmonizes them both around the perfect septenary arithmetical possibilities and traits of this number.

Although some claim that the 364-day year in the astronomical book of the book of Henock is primarily a solar year, possibly because they overstated the primacy of the solar model in chapter 72, this is certainly not the case. The 364-day year is not designated as a solar year anywhere in the Astronomical Book, nor is there a preference for the sun over the moon in the determination of times. On the contrary, it is the purported aim of the astronomical book to achieve a harmony between all heavenly luminaries by means of the Divine mechanism of the 364-day year.

360 day year

The 364-day year finds its core structure in the 360-day year, which consists of 12 schematic 30-day months.

The traditional Mesopotamian astronomy was based on the ideal year of 360 days, which is most suitable for astronomical and administrative calculations. The 360-day year is then completed with the four cardinal days, to reach the number of 364.

The year always begins imminently after the spring equinox as the beginning of the year always falls on a Wednesday. Therefore, the festival of Passover always falls in the first month, following the biblical decree in Exodus chapter 12. The emphasis on the synchronization of the Calendar to the solar movements and its seasons through out the year, is an important characteristic of the 364-day calendar tradition.

It is divided symmetrically into a hierarchical order of time periods, (1 En 82:9–20; Jub 6:29–31; 4Q328, 4Q329)

The Calendar structure underlines the division of the year into 52 weeks and hence into 4 quarters of 13 weeks or 91 days each. The neat division of the year into 52 weeks had great value in the Hebrew culture, where, since biblical times, the number 7 has been considered sacred, laying special emphasis on full weeks (the 1st day of the week Sunday to the last day of the week Sabbath). In this respect the 364-day year is greatly advantaged with regard to the standard gregorian or even Jewish luni-solar calendar, in which the number of days in the year is ever changing with observation.

Therefore, the 364-day year has the great virtue of dividing exactly into 52 weeks, and subdividing into 4 seasons of 13 weeks each, and has the further practical advantage that the annual holidays fall on the same day of the week very year, and never fall on the Sabbath.

The last day of the quarter as an ‘additional day’: the 91st day

The models for solar and lunar movements employed in the Astronomical Book (most notably chapter 72, as well as some literary statements in the framework of the book) had been originally devised according the ideal 360-day year and only subsequently implemented with the additional days.

Throughout the entire range of the sectarian calendrical literature there is a distinction between 360days, which are the ‘days of the year’ in the full sense of the word, and the four additional days.

These special intercalary days are designated by the term Tekufah, and by extension refering to the season. being of different nature, even very similar to modern day the ‘solstice, equinox’.

The tekufot are not marked by the sun’s cardinal points like in modern day "equinoxes & soltices. The 364-day structure being divided into 4 mathematical seasons. These four added days, one in each quarter, constitute the difference between the year of 360 days and the ideal 364-day year. Owing to the fact that the number 364 divides neatly into seven, and since the day of the week in which the beginning of the year falls is fixed, all the dates, festivals etc. in the year will wittingly occur on the very same day of the week. This elegant structure is unique and unmatched by any other calandar, the structure of days, weeks and months in each of the quarters retaining an essential and perpetual symmetry.

For instance, the festival of Unleavened Bread (Mazzot, 15th of the first month) constantly falls on the fourth day of the week, and so does the festival of Tabernacles (Sukkot), on the 15th of the seventh month. The first day of the first month (1/1) also occurs on a Wednesday, and thus also the Day of Remembrance on the first of the seventh month.

In the 364-day year, it is impossible for a day of feast to fall on the Sabbath day, an occurrence which would cause great confusion with regard to the correct procedures in the Temple, and which in fact continue to bother the rabbinic legal experts quite considerably.

Each quarter comprises three months whose days number 30, 30 and 31. The scroll 6Q17 neatly transmits this order of months: “[the first month, in it 30 days. The] second month, in it 30 [days.The third month, in it 31 days,] and completed are the days of [the quarter]” (see also 1 Enoch chapter 72).

The 364-day year contains twelve schematic months. Unlike the Jewish practice which originates from Babylon (Tišri, Tamuz, etc.), the months of the Calendar as in Enoch 1 are numbered according to their order in the year: the first month, the second month etc., similar to the mode of designation in priestly layers of the Pentateuch, such as the laws concerning the festivals in Lev 23 and Num 28–29.

The polemics with the luni-solar traditions have been at play for long centuries. Already the Book of Jubilees & some Scrolls severely reprimanded those who wondered off to following lunar months: " Command the sons of Israel to observe the years according to this reckoning – three hundred andsixty-four days; and these shall make up a complete year. ... But if they neglect the proper orderand fail to observe them ... the all the seasons will get out of order and the sequence of the year will be disturbed. .... Yet all the sons of Israel will forget and be ignorant of the progression of the years; they will forget the new moon and festival and sabbath". (Jub 6:32–38, cp. 23:19)

"I will put an end to all of her joy: her pil[grimages, new] moons, Sabbaths, and all her sacred days”. This means that [all the sacred] days they will take away in exchange for Gentile sacred days, so that [all] [her joy] will be turned into mourning." (4Q166 ii 14–17)

In a series of scholarly articles (1953–1957) Annie Jaubert analyzed the dates appearing in Jubilees, comparing them with the dates arising from the priestly sources in the Hebrew Bible, which predate Jubilees by three centuries or so.

Putting great emphasis on the days of the week as a factor in the priestly calendar, and based on the structure of the 364-day year (above), her surprising conclusion was that the calendar of Jubilees was identical to that which stood behind priestly sources in the Pentateuch, such as the list of the journeys of the Israelites in the Book of Numbers, as well as behind other texts from late books of the Hebrew Bible (ca. 6th century BC). Jaubert discovered that the biblical narratives could be interpreted to show, for example, that the Israelites abstained from travel on the Sabbath day. During the 1950s, preliminary publications of the first scrolls unearthed at Qumran revealed a surprising similarity between the Qumran calendars and those calendars previously studied by Jaubert. Accordingly, the Qumranic 364-day calendar tradition had very early origins in Hebrew antiquity, and that the 364-day year was put to practice in the Jerusalem Temple for the first century. The babylonian civil luni-solar calendar gained hold in Jerusalem only gradually in the Hellenistic period, after the destruction of the Temple. 

However, the yahad community members retained the antique Hebrew calendar of 364 days, while opposing the Pharisaic circles who had chosen to make alliances with Antiochus. 

The 365.24 tropical year & the 364 day Calendar

The 364-day year cannot be labeled as a solar year, for the number 364 is not identical with the length of 365.24 days in the tropical year, leaving a margin of 1.24 days between the two measurements, which accumulates to a significant difference within a short period of time. 

Despite the fact that there is no explicit statement of intercalation in the Scrolls, it is obvious that the community members would have known about its necessity and realigned periodically their time reckoning with the seasons. For instance, the special festivals celebrated by the members of the community such as the festivals of the first fruits mentioned in the Temple Scroll, were dependent on the agricultural year and they would have lost, within a very short time, all connection with the seasons of the year.

Accordingly, because of the perfect scheme of the 364-day year, it becomes the self-evident that the year has been adjusted to the seasons with the unbreakable 7-day block called the "week", as an intercalation, every 5 to 6 years, thus keeping the first day of the 1st month always within 1 to 6 days after the Spring Equinox.

The Epagomenal week

A tropical year is the time that the sun takes to return to complete a full cycle,  from vernal equinox to vernal equinox, and returning to the same position, completing its 360 degree ecliptic cycle. The mean tropical year is approximately 365 days, 5 hours, 48 minutes, 45 seconds, which means the mean solar year lasts 365.2421897 days. Because 1/4 of a day can never be accounted for in any calendar, different forms of intercalation is being by all calendars, in order to solve the concurrence unavoidable cumulative discrepancy.

Indeed, to compensate for this difference, every calendar is obliged to intercalate extra days in order to catch up with the seasons. For instance, the Gregorian calendar intercalates 1 day about every 4 years; the Jewish lunar calendar adds an entire 13th month. 

On the Perpetual Calendar, the Hebrews had to intercalate a united block of 7 extra days, called the epagomenal week. Because they were not part of the normal year, the Hebrews must have regarded these days as particularly discreet. No text has survived listing the hebraic epagomenal week, despite the fact that it is well known that ancient cultures, like Egypt, intercalated their own epagomenal days at the end of their calendar year, when necessary. It is calculated that the Essene had to intercalate their week every 5-6 years in order to remain in sychronisation with the seasons. 

The different intercalations of the Original Calendar 

Intercalations in timekeeping is the insertion of a leap day, a leap week or leap year in order to make the calendar follow specific rhythms. The week in Genesis for instance is composed of 6 working days with an intercalation of a 7th day of different nature. Identically, the jubilee year (the 50th year) is being added as an intercalation to the count of 49 years (7x7).

The lunar aspect of the 364 day calendar

The role of the moon in time-reckoning is supported by many documents in Qumran which record lunar phases. when the phases of the moon are indicated in the calendrical documents, they seem to be indicated schematically and never by actual observation. Despite the many documents enumerating lunar phases, there is no function for the lunar phases in the ritual calendar.

 The religious life of the community was dictated by the arythmetic 364-day calendar alone; the yahad had no festival or sacrifice which depended on lunar movements. 

The 354 lunar year and the 364-day calendar year are synchronized at the end of every three years by means of the addition of a 30-day month