A solution to one of the historical mysteries surrounding the Dead Sea Scrolls, that of the Qumran sect’s unique calendar, has been proposed by researchers from Tel Aviv University (TAU).

For decades, scholars have wondered if Qumran’s 364-day year calender had ever been used in practice. Some have suggested that the sect had periodically added days or weeks to its calendar, while others claimed that the calendar had never actually been used in the real world, serving only as a theoretical framework.

But in a study recently published in the Tarbiz Quarterly for Jewish Studies, TAU Prof. Eshbal Ratzon suggested that Qumran’s 364-day year calender had indeed been used by the sect in its early years. 

Further, she argued that the calender may have even been at the heart of the conflict that drove the sect to its desert isolation.

The study noted that almost 20 of the scrolls found in Qumran deal with calendars and astronomy, a number proving the importance the topic held with the community. 

The Book of Jubilees, Ratzon exlplained, an apocryphal work central to the Qumran library, fiercely attacks the prevailing lunar calendar, presenting the 364-day calendar as the original timeline received by Moses on Mount Sinai.

While Jewish life during the Second Temple period centered on the lunisolar calender, Qumran’s consisted of exactly 364 days: A number perfectly divisible by seven, meaning that every year included 52 full weeks, and holidays would always fall on the same days of the week.

For the Qumran sect, the 364 day calender reflected the perfect divine order.

The calender was also symbol of rebellion against the political and religous leadership in Jerusalem, which would determine the significant dates for Jewish life - a motion that went against the sect’s belief.

It believed that the dates had already been set in place by God during Creation, and humans should not and could not interfere with such a divine ruling.

However, Ratzon noted that the calender was likely later abandoned for two reasons.

The first was that the calender diverged by one day and a quarter from the 365-day astronomical year, a difference that accumulated rapidly and would quickly lead to the shifting around of the festivals, according to Ratzon.

For example, if the Qumran calendar was used for 20 years, festivals would shift by almost four weeks relative to the seasons. After several decades, those in Qumran would end up celebrating a spring festival in the winter or the fall.

For a community that regarded festivals as agricultural celebrations connected to the harvest, first fruits, and seasons, such a shift posed a clear fundamental problem.

The study explained that while the calendar had originally served as an ideal framework from a conceptual and mathematical perspective, over time it drifted further and further away from the natural cycles it sought to govern.

The second reason for the calender’s abandonment, according to Ratzon, was the sect’s warming relations with Hasmonean leadership under its second king, Alexander Jannaeus (103 to 76 BCE), who supported a halacha similar to their own and opposed the Pharisaic leadership.

The move allowed Qumran to adopt a more “practical” calender, like the one used at the Second Temple, while retaining the 364-day calender as a theoretical concept that had been valid at the time of Creation and could potentially be used again in the “End of Days.”

"The Qumran calendar has long been regarded as one of the Qumran sect's defining features, but also as one of the most baffling mysteries of the Dead Sea Scrolls,” Ratzon concluded. “This study proposes an alternative for the seeming contradiction between a functional calendar and a theoretical one.”

“It is quite possible that the calendar was in fact used for a certain period of time, but then, losing its practical role due to both inherent problems and political changes, became a religious ideal and a symbol of identity. This would explain both its centrality in the Qumran scrolls and its gradual disappearance from historical reality."