There is a fundamental difference between Shabbos and Rosh Chodesh. The mitzvah of Shabbos is preceded by “sheishes yamim ta’avod.” There is a mitzvah of preparing for Shabbos. Chazal say that only “mi she’tarach b’erev Shabbos yochal b’Shabbos.” Shabbos is the culmination of the cycle of the week. Not so Rosh Chodesh. Rosh Chodesh precedes the events that will occur in the upcoming month. It sets the tone for what is to be, and does not depend on the energy and preparation of prior events. It is an inauguration, not a conclusion.
Klal Yisrael had known of Shabbos even while in Mitzrayim, but until Pesach, they had not known of the concept of Rosh Chodesh. They understood that for those who put in spiritual work and effort, G-d delivers rewards. What Rosh Chodesh taught them is that G-d can deliver the rewards in advance, and the effort can come later. This is the foundation upon which Pesach rests. Klal Yisrael had little merit to speak of when they left Egypt; “ta’avdun es haElokim al ha’har hazeh” was an event that would occur in the future. Nonetheless, G-d promised them deliverance based on what would be.
That’s why, explains the Shem m’Shmuel, the haggadah has a hava amina of “yachol mei’Rosh Chodesh,” that maybe we could do sipur yetzi’as Mitzrayim from Rosh Chodesh. Rosh Chodesh is the precedent that gives rise to a Chag haPesach.
The gemara (Shabbos 147) tells a story about R’ Elazar ben Arach: there was a place that had great wine and bath houses and the ten tribes that were exiled there were drawn in by the pleasures and vanished. R’ Elazar ben Arach decided he was going to go to that place and check it out. After spending some time there, the gemara says that he got an aliyah (maybe it was parshas hachodesh) and instead of reading “hachodesh ha’zeh lachem” he read the words as “hacheiresh haya libam” – their heart was deaf. The Chachamim davened that his learning should be restored, and learned a lesson that even a talmid chacham should be “goleh l’makom Torah” and not think he can live removed it.
Taken at face value, it’s an incredible story. This is the same R’ Elazar ben Arach about whom R’ Yochanan ben Zakai said that if all the other Chachamim were placed on one side of a scale and R’ Elazar on the other, he would outweigh them all. How can this same R’ Elazar ben Arach go so far astray as to not even be able to read a pasuk in chumash correctly?! From a mussar perspective, I guess you would say that that’s exactly the point – even someone so great can fall to the lowest depths. But maybe there is more to it than that.
If you’ve ever davened mincha in, for example, a ba’al teshuvah yeshiva, you can find people focusing on every word of davening like it’s Yom Kippur. Meanwhile, the guy who has been davening mincha for the past 30 years knocks off his shmoneh esrei in three minutes flat. The thrill is gone; the newness, the freshness is gone. We don’t remember what it’s like to daven for the first time. R’ Elazar ben Arach could have been one of the biggest Roshei Yeshiva and said shiur on the same cycle of 7 masechtos again and again for decades, but he knew that if that’s what he chose to do, he risked losing that freshness and newness that comes with seeing things the first time. So he sought out people who could see things for the first time – he went out to the boondocks and started a kiruv movement in a place where there was nothing left of Judaism and where the lure of hedonism drew everyone in. He went out and lived among people who, when they discovered Judaism, saw it as new and fresh. R’ Elazar knew that in order to experience “hachodesh hazeh lachem,” hachodesh = chadash, newness, freshness, you need to first have “hacheiresh haya libam.” Sure, putting himself in that situation was a challenge and a step down from the amazing shiurim R’ Elazar might have been saying, but it ultimately was a step up, because the vitality of those around him would rub off and R’ Elazar himself benefit from that constant rejuvenation.
That’s the upshot of the gemara, explains the Chernobeler in his Ma’or Eynaim. “Havei goleh l’makom Torah” – you have to sometimes go out, go into galus, go to the boondocks, and there you will find Torah as it should be experienced, as new, as fresh, as filled with vitality. The truth is that you don’t have to travel too far. There are plenty of souls that are deaf to Torah all around us because no one has come along to open their ears. The truth is that we each have a little bit of “hacheiresh haya libam” in us, but if we help each other out we can transform it into “hachodesh (=hischadshus) hazeh lachem.”