Astronomy – calculating the new moon

At the beginning of the Chumash, Rashi asks why the Torah begins with the story of creation instead of mentioning the first mitzvah of Kiddush Hachodesh. One could just as easily ask another question – why was Kiddush Hachodesh indeed the first mitzvah given to us in Egypt?

The simple answer is that this mitzvah was essential in order to establish the 14th of Nissan when we would bring the Korban Pesach, since without months there cannot be Yom Tov. At that time, not one Jew had the faintest knowledge of the secrets of the Jewish calendar, known as Sod Ha’Ibur.

LOST SECRET                                                                                                                  Sod Ha’Ibur is actually two secrets in one, including both ibur hachodesh, determining whether to make the month 29 or 30 days long, and also, ibur hashanah, the necessity of sometimes adding a second Adar in order to reconcile our lunar calendar with the solar year.
How was Sod Ha’Ibur forgotten? According to Pirkei d’R. Eliezer (ch. 8), Hashem taught Adam Harishon the Sod Ha’Ibur in Gan Eden. Then, “Adam passed it over to Chanoch… Chanoch passed it over to Noach… Noach passed it over to Shem, and Shem passed it over to Avrohom…” But after Yosef and his brothers died, the Jews forgot it due to the terrible servitude of Egypt. And this amnesia was a sign for the future. Thousands of years later, the Jews would once again forget the sod Ha’Ibur during our fourth exile and just as Hashem had returned Sod Ha’Ibur to Moshe and Aharon in Egypt, so he will return it to us at the coming redemption.

According to this approach, select individuals knew the Sod Ha’Ibur since the time of the creation. Thus, when the Torah writes that the flood lasted from the 17th of the second month until the 27th of the second month, Noach himself may well have calculated these two dates.

In contrast to Pirkei d’R. Eliezer, the Pesikta d’Rav Kahana (ch. 5) insists that no one on the planet knew Sod Ha’Ibur until the Jews left Egypt. “All those 2,448 years until the Jews left Egypt, the Holy One was sitting and making calculations and leap years, and sanctifying years and renewing months. Once Yisroel left Egypt, He gave it to them.”

We can now offer a deeper reason why Hashem gave us Sod Ha’Ibur as our first mitzvah. This mitzvah indicates that at Yetzi’as Mitzrayim Hashem appointed us His am segulah by entrusting us with this secret system that distinguishes us from every other nation.

As the Pesikta d’Rav Kahana (5:46) expresses it: “You will be holy to Me… and I will separate you from the nations (Vayikra 20:26). Yisroel are different than the nations of the world in all their deeds, in their plowing, in their sowing, in their reaping… in their counting and in their calculations… because the nations of the world count according to the sun, and Yisroel according to the moon…”

The Shemos Raba (ch. 15:27) adds that the two modes of counting time symbolize our destiny in contrast to that of the world — just as the sun is by day, so they only rule in this world. And just as the moon is by day and by night, so Yisroel rule in this world and the world to come.

In a similar vein, the Medrash Raba (Shemos Raba 15:26) writes that our calendar symbolizes that we live not according to the laws of nature symbolized by the sun, but through Divine providence. Just as the moon waxes and wanes, so our fortunes rise and fall solely according to our spiritual level. The thirty days of the month represent the wax and wane of Jewish history:

Before the Holy One took Yisroel from Egypt he already hinted to them that their kingdom would only last for thirty generations as it says, This month is for you the head of months. The month is thirty days and your kingdom will last thirty generations. The moon begins to shine on the first of Nissan and it becomes ever brighter until the 15th day when its disc is full. From the 15th day until the 30th its light lessens and on the 30th it is invisible.

“So it is with Yisroel. There were 15 generations from Avrohom until Shlomo… and from then on the kings began to be less great… [This continued until the 30th king] Tzidkiyahu came, of whom it says, They blinded Tzidkiyahu’s eyes (Melachim II 25:7), [and in that generation] the moon’s light disappeared…”

The Pesikta Raba (15, 77b) expresses this even clearer, “[You are] like the moon. If you merit you count to its filling [and become greater meriting leaders like] Avrohom, Yitzchok, etc. If you do not merit you count to its lessening [and have leaders who become progressively smaller such as] Rechavam, Aviya, Assa, etc.”

According to Medrash Sod Ha’Ibur, Sod Ha’Ibur gave us yet another distinction: to manipulate time according to necessity. “At that time… even though the Holy One taught Moshe Rabeinu which years are regular and which ones are leap years,” the Medrash says, “he gave him and the Sanhedrin with him in every generation, [the power] to establish the times as they want. So that if they decided to make a regular year into a leap year they can do so… as it says, These are the appointed times of Hashemthat you will call them in their time (Vayikra 23:4). The keri’ah is given to you, and all that Sanhedrin does is done.”

The Tanchuma Yashan (Parshas Bo ch. 8) takes this idea further, saying that on occasion the sages even had physical control over the moon’s appearance: “This month is for you. It is given to you and you are not given into its hand. There was an incident regarding Rabbi Chiya the Great that the moon rose on the day before Rosh Hashanah and cattle herders traveled three miles by its light. Rabbi Chiya saw it and took clumps of dirt and threw [them] at it, saying, ‘We want to renew you tomorrow and you have risen now?’ Immediately, it disappeared in its place. Why? Because it was under his jurisdiction.”

Why was Sod Ha’Ibbur kept such a close secret?

The Rambam Hilchos Kiddush Hachodesh 11:8) offers the simplest answer. This system remained secret due to its depth and intricacy: “Regarding these principles we have traditions from the mouths of sages and proofs that were not written in seforim known to all, etc. Because these matters are very distant and deep, and this is the Sod Ha’Ibur that the great sages knew of, and they did not reveal it to everyone, but only to people who had semicha and understanding.”

In contrast to the Rambam, the Sefer HaYisraeli (Yesod Olam 4:14) writes that this knowledge was withheld even from great people worthy of understanding it and restricted to a select few in order to minimize disagreements.

“The reason it was not fitting to reveal the Sod Ha’Ibur to Yisroel and even to the wise among them was as follows. Sometimes Beis Din in earlier times made a leap year because of the [winter] season, and sometimes because spring which had not yet arrived, and sometimes because of [unripe] fruit and other signs given to them at Sinai. And at other times they made a leap year for needs of the times as seemed to them….

“Yisroel knew nothing of this and did not scrutinize the matter because they did not know the secret of its tradition. However, if they had known, people in Eretz Yisroel may have sometimes argued against the Beis Din according to their investigations and calculations… and this would lead to great controversy and corruption of the times as happened in the story of Rabban Gamliel and R. Yehoshua…[when they argued about the date of Yom Kippur]” (Rosh Hashanah 25a).

Rav Tudrus HaLevi Abulafia who lived in Spain during the thirteenth century takes a totally different approach in explaining why Sod Ha’Ibur is described as a secret. In his Sefer Hakavod (Rosh Hashanah 21a) he writes that Sod Ha’Ibur is not merely a mechanical calculation of time, but a process fraught with deep mystical significance upon which all the secrets of the Torah depend. In support of his contention we find that the ceremony of Kiddush Hachodesh sometimes involved the direct manifestation of the Divine Presence:

“…They spread their hands to their Father in heaven, and the Rosh Yeshivah mentions the Name with great sanctity [some texts have: ‘Greater than that of Yom Kippur with the Kohein Gadol who mentioned it seven times…’], and they hear a heavenly voice that cries out and says as follows, And Hashem said to Moshe and to Aharon [etc.]. But if the generation is sinful they hear nothing and, as it were, His presence cannot dwell with them. Happy are those who are there at that time” (Pirkei d’R. Eliezer).

After many centuries, Klal Yisroel ceased using the complicated Sod Ha’Ibur system. This happened seven years after the passing of the famous Rava in 4119/359, when Hillel II began a permanent calendar based on four simple rules that even an intelligent child can comprehend. Surprisingly, this milestone in Jewish history is explicitly mentioned nowhere in Shas or the Medrashim, first appearing in Sefer Ha’Ibur of Rav Avrohom bar Chiya in the name of Rav Hai Gaon.

Why did Hillel take this drastic step of transforming our calendar? One reason is that he realized that semicha would soon disappear leaving no one qualified to declare new months. Another reason was the pressures of the times, “so that it was difficult to find witnesses to go and testify before Beis Din, and messengers could not go out to all the places and announce the Kiddush Beis Din due to difficult traveling conditions” (Sefer Hamaor Rosh Hashanah ch. 1).

In addition, there was a danger that differences of opinion might lead to various groups observing Yom Tov on different days, and lead to an irreparable rift in Klal Yisroel.

However, as mentioned earlier, Hillel II’s new luach was only a stopgap measure. Once Eliyahu Hanavi and the Moshiach restore Sanhedrin and semicha, we will once again determine Rosh Chodesh with the erstwhile system Moshe and Aharon used at the birth of our nation.

(Source: Kasher, Rav Menachem M. Torah Shleimah. “Parshas Bo”)

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