The Calendar of the Book of Enoch: A Year of 364 Days

In the calendar of the Book of Enoch, your birthday would always fall on the same day of the week: this year, next year, and every year after that. The new year would always begin on a Wednesday, the Passover Seder would always be on a Tuesday evening, and no festival would ever fall on the Sabbath. There would be no need for a calendar on the wall. Whoever learned the year once would know it for ever.

It sounds like a modern engineer’s dream. In fact, this calendar was written more than two thousand years ago, and it was one of the subjects over which Jews in the Second Temple period argued most bitterly.

How a year of 364 days is built

According to 1 Enoch, the year has exactly three hundred and sixty-four days. The year is divided into twelve months of thirty days, and at the end of each quarter one day is added. So every quarter has ninety-one days, which is exactly thirteen weeks, and the whole year has fifty-two weeks, with nothing left over.

The book devotes a whole section to the subject, the Book of the Luminaries, chapters 72 to 82. The angel Uriel shows Enoch six gates in the east and six in the west, through which the sun rises and sets. Each month it moves to a different gate, and the day grows longer or shorter accordingly. The book measures the length of the day in parts, eighteen to a full day and night, and on the equinox nine of them are day and nine are night. At the end of the reckoning comes the declaration:

For they belong to the reckoning of the year, and they are truly recorded for ever: one in the first gate, one in the third, one in the fourth and one in the sixth. And the year is complete in three hundred and sixty-four days.

1 Enoch 82:6

The “they” in the verse are the four additional days. The author knows that some people forget to count them, and he warns: people go astray over them, and do not reckon them in the count of the year.

The beauty of the number

To understand what is so attractive about this calendar, you have to think about the number seven. Three hundred and sixty-four divides by seven with nothing left over. This means that the week and the year are perfectly synchronized. If the year begins on a Wednesday, it will always begin on a Wednesday.

And why Wednesday? Because according to Genesis, the luminaries were created on the fourth day. Time cannot begin before there is a sun to measure it. Everything else follows from this. Passover always falls on a Tuesday evening, the Day of Atonement always on a Friday, and no festival ever collides with the Sabbath.

For anyone who sees a divine order in the world, this is almost a mathematical proof. Creation, the Sabbath and the festivals mesh together like gear wheels. The calendar is not an agreement between people. It is a law of nature, set in heaven and handed to Enoch.

Who followed this calendar

The Book of Enoch is not alone. The Book of Jubilees, written in the second century BCE, adopts the same year and fiercely attacks those who count the months by the moon. In its words, they confuse the appointed times and turn a holy day into an ordinary one.

In the Qumran scrolls this calendar is no longer an idea. It is a working calendar. Detailed lists of the priestly courses were found there, arranged according to a year of three hundred and sixty-four days. One of the scrolls says that King David composed three hundred and sixty-four songs, one for every day of the year. And another scroll tells that the leader of the sect was pursued by his rival, the priest in Jerusalem, on the Day of Atonement itself. That is possible only if one man’s Day of Atonement was an ordinary weekday for the other.

The rival calendar

The calendar used in the Temple, and later adopted by the rabbis, works differently. In it the month is set by the new moon, and is twenty-nine or thirty days long. Twelve lunar months fall short of the solar year by about eleven days, so every few years a whole month is added, to keep Passover in the spring. This is the Hebrew calendar we know.

It is more cumbersome, and in it the festivals wander among the days of the week. But it has one great advantage: it rests on what can be seen with the eye. Anyone can look at the moon and know where they stand in the month.

A dispute over a calendar is not a technical matter. A community that celebrates its festivals on different days cannot pray, fast or offer sacrifices together with everyone else. Whoever controls the calendar controls shared time. It is hard to find a more effective way to separate from the community, or to be pushed out of it.

The small problem

The calendar of the Book of Enoch has one flaw, and it is not a minor one. The real solar year lasts three hundred and sixty-five days and about a quarter. A year of three hundred and sixty-four days falls behind it by a day and a quarter every year. Within twenty-five years the gap reaches a whole month, and within a few generations the spring festival falls in the middle of winter.

How did the people who followed this calendar deal with that? We do not know. The sources we have contain no explicit instruction to add days or weeks, and scholars disagree about whether any correction was made.

The Book of Enoch itself offers an original solution. Chapter 80 says that in the days of the sinners the years will grow shorter, the rain will be held back, the moon will change its order, and many stars will stray from their paths. In other words, if the sky does not fit the calendar, the problem is with the sky. It is hard not to smile at this, but anyone who has ever tried to fit an unruly reality to a perfect plan will recognize the temptation.

Where the reckoning came from

One detail in the book gives away the source of its knowledge. According to the Book of the Luminaries, the longest day of the year is twice as long as its night. That ratio does not fit the Land of Israel, where the differences between summer and winter are much milder. It is familiar from the astronomy of Babylon, where people had been calculating this way for centuries before.

So the authors of the Book of Enoch took ancient Babylonian knowledge and fitted it onto a seven-day week and the story of creation. Even 2 Enoch, written later, is no longer faithful to this calendar, and speaks of a year of three hundred and sixty-five and a quarter days.

The dream of a perfect calendar

The idea did not die. In modern times, too, fixed calendars have been proposed again and again, in which every date always falls on the same day of the week, and some of them are based on exactly the same reckoning: three hundred and sixty-four days, with an addition from time to time. None of them has been adopted.

The reason is probably the same reason. A calendar is not only a measuring tool. It is an agreement between people, and agreements are not replaced because someone has proposed a more elegant calculation. The authors of the Book of Enoch believed they had discovered the calendar set in heaven. Their opponents made do with the calendar most people agreed on. History, as it tends to, preferred the agreement.