Why the date of the holidays are dependent on the Jewish people’s sanctification:[1]
In contrast to the Shabbos which is set to the seventh day of the week, the holidays are set according to the dates of the Jewish month. Now, while the dates themselves are set and not subject to change, such as the 15th of Tishrei to celebrate the Sukkos holiday, nevertheless, the establishing of the date in which the new month begins is dependent on the sanctification of the Jewish people. In essence, it ends up that the Jewish people decide the exact day of the week that the Hebrew date of the holiday will fall on. It is for this reason that in the middle blessing of the Yom Tov prayer we recite the wording of, “And he sanctifies the Jewish people and the times,” as the date of the holiday is dependent on the Jewish people. Now, what is the mystical reason for why Hashem made it that the date of the Shabbos is not dependent on the Jewish people while the date of the holidays are?
The reason for this is as follows: The vast majority of the holidays fall on the weekdays which are days that are mundane of holiness. Now, how is it possible to turn a mundane weekday into a holiday? It is precisely for this purpose that it is necessary for the Jewish people to sanctify the month and establish the exact date of the holiday. The Shabbos is an intrinsic day of holiness and does not require the intervention of the Jewish people to make it holy, and hence its date is not determined by us, in contrast to the holidays. Now, how do the Jewish people accomplish the sanctification of the weekday to make it an abode for the holiday? Through sanctifying the new month. During the sanctification process, and through the fulfillment of the Mitzvah of Kiddush Hachodesh that it involves, the Jewish people draw down a level of holiness to the weekday that allows it to become a holiday.
In detail, this works as follows: A regular weekday corresponds to the external level of Chesed and Gevura of Atzilus while a holiday corresponds to the high level of supernal wisdom known as Chochmah Ila’ah. It is not possible for the weekday on its own to make the big leap from its external level of the supernal emotions to the internal level of divine wisdom without the help of the Jewish people. This is accomplished with the help of the Jewish people through them sanctifying the new month. Through doing so we draw a ray of the supernal wisdom onto the weekday and hence allow it to eventually become elevated as a holiday to the internal level of Chochmah Ila’ah.
How the Jewish people have such power: What still remains to be understood is how the Jewish people have this great power to access the level of supernal wisdom and actually draw down a ray from it onto the weekday. This will be explained next based on the idea that every Jew is an emissary of G-d.
[1] Likkutei Torah p. 1a-2a
