In addition to the regular weekly reading, this Shabbat includes a special reading, since it is Shabbat ha-Ḥodesh, the Shabbat that falls before or on the first day of the month of Nisan. This special reading is Exod 12:1-20, which begins with God instructing Moses and Aaron, “This month is to be the beginning of the months for you: it is the first of the year’s months for you.” The verse may seem bit repetitive, but the message is clear: the Hebrew calendar is to start in “this month,” that is, the month we call Nisan.
It is therefore somewhat surprising to find that various midrashic comments on this verse take it in an entirely different direction. The word “This,” they says, indicates that the Holy One actually pointed to the new moon and said to Moses: “When you see [the new moon] like this, proclaim the new month.”
To understand the point of this remark, you have to know something about the great calendar dispute that took place within Judaism in late Second Temple times. While our own spiritual forebears endorsed the Hebrew calendar more or less as we know it today, other Jews favored a very different calendar. In it, each month was to be exactly 30 days long, and the beginning of the month had nothing to do with the phases of the moon. The beginning of the next month started the day after the 30th day of the previous month, no matter whether the moon itself was a half-moon that day, or a quarter-moon, or whatever.
Twelve of these 30-day months made for a total 360 days. Four additional, free-floating days were added and placed at the four cardinal points of the year, bringing the total up to 364 days. (This was the system reflected in the book of Jubilees; the Dead Sea Scrolls reveal a slightly different system, in which every third month was 31 days long thus eliminating the need for free-floating days; but the result is the same—364 days in all.)
We don’t have much of an idea about what percentage of the Jewish population used this other calendar, but the number may well have been considerable. Note that this system still fell short of the solar year by 1 and ¼ days, and scholars are also not sure how the gap was made up. (According to the book of Jubilees, it seems that the shortfall was made up by adding an extra day at the end of each year, two days at the end of every fourth year. In the system evidenced in the Dead Sea Scrolls, the shortfall was apparently compensated by adding an entire week at regular intervals to bring things perfectly in line with the solar year.)
Which system does the Torah endorse? Actually, the Torah never says. It talks about the months (“In the third month, on the first day…” and the like), but it never explains what a “month” is to consist of. Hence the midrash cited above. It presents God as pointing to the new moon and saying, in effect, “Determine the months by the spotting the new moon, that is, when it looks like this,” effectively ruling out the calendrical system endorsed by the Dead Sea Scrolls community and other such groups.
But which system was better? This is not a simple question, but the system found in the Dead Sea Scrolls had a lot to say for itself. The transition from month to month was automatic—no need for humans to spot the new moon in the sky. Moreover, an official calendar of 364 days, even if it fell 1¼ days short of the solar year, was never far out of sync with the sun. Finally, the various annual festivals—Passover, Sukkot, and so forth—always fell on the same day of the week.
Compared to this, the Hebrew calendar was a clumsy tool. Every few years, at irregular intervals, a whole month had to be intercalated, that is, a second month of Adar had to be added to the twelve months that had already passed. This insertion of an entire month was a big jolt vis-à-vis the solar year, compared to the mere addition of a few days in the other system. As Jews still like to say of the Hebrew calendar, “Rosh ha-Shanah is early this year,” or “Passover is late”—by which they mean “early” or “late” vis-à-vis the more-or-less solar year of the civil calendar. But the other system basically kept pace with the solar year, requiring only minor adjustments.
Nowadays, you can get a Hebrew calendar that tells you when each month begins. But in ancient times, two reliable witnesses who had spotted the new moon had to go to a special place in Jerusalem called Beit Ya‘azek and testify that they had seen it; they were then cross-examined to make sure that the testimony of both witnesses agreed. Only then could the new month be proclaimed—and the word had subsequently to be spread to Jews near and far.
Why did our spiritual ancestors not adopt the simpler, automatic, calendar? No doubt many factors were involved. But it seems important to point out one thing: they apparently did not mind the fact that their system required human intervention. In fact, our Rabbis seemed to glory in the “human factor.” Human beings had to spot the new moon in the sky and then get to Jerusalem to say they had spotted it; then they had to be cross-examined by other human beings, and after that, the word had to go out to Jews elsewhere—again, through human intervention. Moreover, human beings expert in such matters had to determine when to intercalate an extra month (there was nothing automatic about when an extra Adar had to be added in those days), and after this, human beings were again needed to get the word to Jews living elsewhere.
All this seems extremely significant for what it says about Judaism in general, as indeed our own sources demonstrate. A verse in the Torah (Deut 30:12) says that the Torah “is not in the heavens.” The Talmud presents a slight modification of this assertion: the Torah “is no longer in the heavens”—that is, it was given by God, but then it was handed over to human beings to interpret and adjudicate. This is the basic idea of the handoff, a central principle in Judaism: what starts in heaven is passed on to human beings on earth to understand and apply. So it is human beings, the best of our sages, who are given the responsibility for establishing the meaning of a text, or how exactly this or that commandment is to be put into practice.
In the case of the calendar, the prayers established by the Rabbis state the matter openly. On the day of Rosh Ḥodesh we praise God for having handed over to us the responsibility for determining the first day of each month, and hence, the day on which all festivals (Passover, Shavu‘ot, and so forth) and even Yom Kippur will occur. God has handed over this responsibility to the people of Israel rather than leaving it to an automatic calendar. That is why we say, in the musaf prayer for Rosh Ḥodesh, that He has “established for them [the people of Israel] the rules governing new months; therefore, blessed are You, for having sanctified Israel and the beginnings of months.”