The Secret of Leap Year: How Did the Sages Preserve the Times of the Holidays?

This week, we learned in the daily page about the leap year.

What is a leap year, and why do we need it?

A year, as known, is the time it takes for the Earth to orbit the sun once, completing the four seasons of fall, winter, spring, and summer. This cycle takes 365 days, and indeed, the Gregorian year is 365 days long.

However, the Hebrew year is counted by months. A month is determined by the appearance of the moon, a full orbit of the moon around the Earth. This orbit takes about 29 days and a bit more than half a day. If we multiply by 12, we get only 355 days, the count of Shana.

This gap of ten days accumulates. Indeed, Muslims, who count only by the moon and do not know how to insert leap years, have their seasons shift backward. A holiday that was once in the summer is now in the winter (because the Quran states that changing the months is a great sin, and it cannot be that in one year a month is like this and another year not). But the Torah requires the holidays to be at a fixed time: Passover must be in spring, and there is a special commandment "'Observe the month of spring'".

Therefore, we insert leap years. Once every few years, an additional month is added, Adar II, and in this way, we maintain the synchronization between the solar months and the lunar months. We have an organized cycle of 19 years, during which seven years are leap years: 3, 6, 8, 11, 14, 17, 19. This ratio of seven out of nineteen gives the best solution to absorb the gap between the solar year and the lunar year.

This calculation was established by Hillel, the last president of the House of David, about 1600 years ago. But until the time of Hillel, the leap year was determined each year by the great court, according to various considerations. Every year in the middle of winter, the sages would gather in a special place for an assembly called "The Secret of the Leap Year." There they would discuss whether to make the current year a leap year or not.

Our fixed cycle sometimes ignores specific needs of the current year. For instance, the sabbatical year. When the leap year was determined each year by the sages, they would not make the sabbatical year a leap year, because it is already very difficult to adhere to the various prohibitions of the sabbatical year, so it would not be right to extend this year by another full month. And sometimes there are other reasons. Our text says: "The Rabbis taught: For three things, the year is made a leap year: for the spring, for the fruits of the tree, and for the period. On two of them - a leap year is made, and on one - it is not." That is, there are three possible reasons: spring has not arrived, rain is still falling, and the month of Nisan is approaching; the fruits of the tree are not yet ripe; and the period - the astronomical signs show that the sun's revolution is far from reaching the spring season. To make a leap year, there need to be two reasons.

But it is still not that simple because it may be that the fruits of the tree in the sunny lowlands of Judea have already ripened, while in the Upper Galilee, they have not yet. Thus, the Baraita establishes a rule here: "The Rabbis taught: For three lands the year is made a leap year: Judea, Transjordan, and the Galilee. For two of them - a leap year is made, and for one - it is not."

That is, if only one area "lags" in terms of the fruits of the tree or the weather, this is not a reason to make a leap year, at least two out of the three regions: Judea, Galilee, and Transjordan, need to have at least three signs.

But these signs are not the only determinants. All this was considered by the sages in their sitting until they reached a decision, and the Talmud mentions a copy of a letter sent by the elder Rabban Gamliel through his scribe Yochanan, which read:

"To our brothers in the Upper Galilee and to our brothers in the Lower Galilee, may your welfare increase, we inform you that the time for the disposal of tithes has arrived, to separate tithes from the olives. To our brothers in the Diaspora of Babylon and our brothers in Media, and to all other dispersions of Israel, may your welfare increase, we inform you that the fledglings are still tender, and the kids are weak, and the time of spring has not yet arrived, and it is agreeable to me and my colleagues to add thirty days to this year."

In his words, we see another consideration: the kids are weak, and thus they will not be able to offer them as the Paschal offering. Before Pesach, very large numbers of kids were required. Another consideration mentioned in the text is the mud on the roads: if the festival of Pesach arrives too early, the roads are still muddy, and this makes it very difficult for those who ascend to Jerusalem.

The talmudic discussion has more fascinating debates on the different aspects of the leap year.