The least observed of biblical holidays is undoubtedly Rosh Chodesh. As a holiday based in the Temple, with no home or synagogue based rituals, there is little to distinguish Rosh Chodesh from any other day.
Yet in the Torah itself, Rosh Chodesh is a most important day—and with 12 of them a year, it is arguably the most important of the biblical holidays. It is the mitzvah of kiddush hachodesh, the sanctification of the new moon, that was the first mitzvah given to the Jewish people; and Rashi wonders why the Torah does not begin with this mitzvah. It is not coincidental that the Mishkan was dedicated on Rosh Chodesh. A simple look at parshat Pinchas, which details the korbanot brought on special occasions, indicates that Rosh Chodesh is the first of our special holidays. As per all biblical holidays, a korban olah consisting of bulls, rams and sheep is sacrificed, along with a he-goat as a sin offering.
That we would offer a korban olah, an offering totally dedicated to G-d, is readily understandable. Less clear is why we must bring a sin offering on our holidays. Yet when viewed in the context of the Chumash as a whole, it appears self-evident why we must both bring a sin offering and why it must be a goat.
It was the goat that was used no less than three times in sefer Breisheet as a means of deception. Yaakov placed the skin of a goat on his arms in order to trick his father into thinking he was Eisav. Yehuda sent a goat as payment for sleeping with one “he took for a harlot” (Breisheet 38:15). And most significantly, the brothers dipped Yosef’s coat in the blood of a goat as they deceived their father as to the fate of Yosef.
It was the sale of Yosef that led to our descent to Egypt and thus on our holidays, where remembering the Exodus is so central, we must recall the dipping of a coat in the blood of a goat. Infighting is the best way to ensure our exile, whether it be in Egypt or anywhere else.
But this explanation does not readily apply to Rosh Chodesh, which at best celebrates the Exodus only indirectly, focusing instead on the sanctity of time. The Talmud (Chulin 60b), most audaciously and somewhat (or more) heretically, offers its own explanation for the bringing of a sin offering on Rosh Chodesh. While the first part of this teaching is well known, being quoted by Rashi (Breisheet 1:16), the latter (and “heretical”) part is less so.
Noting the contradiction between G-d’s creation of “the two [equally] great luminaries” and “the greater luminary to rule in the day and the lesser one in the night”, Rav Shimon ben Pazi envisions a discussion between the moon and G-d. When G-d told the moon to lessen itself after it had noted the impossibility of “two kings to wear one crown” (and it is here that Rashi ends), the moon retorted, “Because I have suggested that which is proper, must I then make myself smaller?” Back and forth it goes, with the moon offering a solid retort for every argument that G-d puts forward. Seeing that the moon was “not placated”, the Holy One, blessed be He, said: ”Bring an atonement [i.e., a sin offering] for Me for making the moon smaller’.
One might have argued that G-d did not actually sin, and only insisted a sin offering be brought on Rosh Chodesh to “placate” the moon, who mistakenly thought G-d acted “incorrectly” in having its size diminished. However, as Reish Lakish notes, only regarding the sin offering on Rosh Chodesh does the Torah say it is brought for G-d. “Why is it that the he-goat offered on the new moon is distinguished in that there is written concerning it ‘unto the Lord’? Because the Holy One, blessed be He, said: Let this he-goat be an atonement for Me for making the moon smaller”. It is because G-d “sinned” that we, his partners in this world, are to bring a sin offering on His behalf.
To say this Gemara is astounding would be quite an understatement. The Torah itself describes G-d as “a faithful G-d, with no iniquity; righteous and moral is He” (Devarim 32:4). Nonetheless, Reish Lakish has no compunction suggesting that G-d needs to bring a sin offering. How this impacts our understanding of G-d, I will leave to biblical exegetes and philosophers. But as one who understands that whatever we are told about G-d is primarily a message for those created in His Image, Reish Lakish’s teaching is most pertinent.
Making mistakes is inherent and is built into creation itself. If even G-d can make—and more importantly, admit—to making mistakes, how can any human refuse to acknowledge the wrong they have done? We often need others to point out our errors. It took the moon to convince G-d that His actions required atonement. It was the moon that created the template allowing us to “challenge G-d”, one taken up so effectively by Avraham Avinu and Moshe Rabbeinu.
It is most interesting to note that of all the mitzvot in the Torah, it is only regarding kiddush hahodesh, the sanctification of the new moon, that we have the halachic notion that errors are to be ignored. When the court declares it to be Rosh Chodesh, it is Rosh Chodesh, even if the ‘moon sighting’ may have been in error.
Rosh Chodesh celebrates the imperfections of life, the mistakes we all make. By being human, we are being G-dly. No wonder it is the first mitzvah given to the Jewish people.
 On Rosh Chodesh, Pesach and Shavuot, it is two bulls, one ram and seven sheep that are to be offered. On Rosh Hashanah, Yom Kippur and Shmini Atzeret it is one bull, one ram and seven sheep. (Is it any wonder that Shmini Atzeret has taken on much of the serious mood of Rosh Hashanah and Yom Kippur?) With Sukkot being a double holiday—the culmination of both the shalosh regalim and the High Holidays of Tishrei—the sacrifices are doubled, so that we bring two rams and 14 sheep each day. The 70 bulls brought over the course of the holiday reflect our hope and prayer that all nations of the world will learn to dwell in peace. There is much we can learn by simply looking at the korbanot brought on each festival.
 Similarly, that each family would have to bring korbanot shelamim, peace offerings that are then eaten, is most logical.
 We are also commanded to specifically remember the Exodus on Shabbat, but that is a reminder that we dare not enslave others; all are entitled to a day of rest.
 It would be silly to think that Rashi censored the second half of this teaching due to its audacious claim. It’s not like one who knew how to read Rashi could not find it. Rather, it’s a function of Rashi’s use of Midrash in his commentary where, more often than not, he will quote only part of a Midrash, and often quote the teaching of a Midrash on a different verse than the Midrash itself. For an analysis of Rashi’s use of Midrashim, please see Nehama Leibowitz, Torah Insigts (Jerusalem: Eliner Library, 1995), 101-143.