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Bo 5763

By: Rav Ari Shames

I would like to focus on the first mitzvah mentioned in this week's parsha- kiddush Hachodesh. (Last year we discussed the significance of the structure and placement of the mitzvah at this point in the torah and we dealt with the famous first Rashi on the Torah which refers to this issue. Please see

The Torah tells us that we are to set up our own calendar. In a nut shell, the system is based primarily on the lunar cycle, with adjustments made in order not to lag behind the seasons of the year, as the seasons follow the solar cycle. Due to the fact that the lunar year is only 354 days long and the solar is 365 we need to have leap years, as is this year, seven times in every 19 years in order to close the gap. (My sincere apologies to my more technical readers for not going into more detail and for oversimplification. I am aware that the above facts are approximate in nature and only serve to illustrate the point. I am certain that an exhaustive discussion of the details would not leave me with many readers for the "exciting" parts to come).

The purpose of the new calendar is to provide us as a new nation with a frame of reference that we are to carry with us forever which revolves around the exodus from Egypt. This singular event is meant to give meaning to our lives by forming the very basis of our system of time. (See the Ramban in his comments on the passuk).

This all seems very nice however the problem is that the torah doesn't seem to come out and say it. The torah never says "make this Rosh Chodesh" or "establish a calendar" in the same way that we are used to seeing other mitzvot presented. In this very parsha we are given all of the mitzvot of korban peasach, tefillin, bechor etc.. all of which are phrased in a very direct manner. Not so for our mitzvah. The torah says "Hachodesh hazeh lachem rosh chodoshim" "This month should be the first", there are no details as to the set up of the system, or as to the procedure which is detailed in the Mishna and gemara for interrogating of witnesses and declaration by the Bet Din. There is no talk abut how to do this in circumstances that we do not have a Bet Din. We are left with a general statement "make this the first month".

This ambiguity led to two interesting debates.

Definition of the Mitzvah-

What exactly is included in the definition of the mitzvah? The Rambam in the Sefer Hamitzvot (aseh 153) writes that the obligation is to "calculate the months and years" and he quotes our passuk as the source for the mitzvah. This definition is surprising in that he included not only the calculations of the months but added as well, the years. This does not seem to have any clear basis in the passuk which seems to refer only to the months. In fact the Rambam himself in the introduction to Hilchot Kiddush Hachodesh, where he defines the mitzvah again writes " to calculate and know the beginning of each month". Here he focuses solely on the months and ignores the years. (There are many instances of discrepancies between the various lists of mitzvot that the Rambam composed and a wide literature exists to help us navigate the issues at hand).

The Sefer Hachinuch (mitzvah 4) defines the mitzvah in an even broader manner. He writes that the mitzvah is to " declare (lekadesh) rosh chodesh to make leap years...and to establish the holidays based upon the declaration". The chinuch is adding not only the calculation of the years but each and every holiday which is celebrated on the day determined based on its rosh chodesh is part of this mitzvah. He goes on to explain that the final purpose of the entire endeavor of the calendar is to establish the holidays and therefore we need all of the elements to do so. We need to calculate each rosh chodesh and use the leap year tool to balance the seasons in order to guarantee Pesach being in the spring.

I believe that the discussion concerning the definition of the mitzvah stems from the lack of clarity in the passuk as to what it is that we are meant to be doing. Are we to read the passuk as an independent unit or is it really an introduction t the entire perek, which delineates various things that must be done on the 10th of the month, the 14th and between the 15th and 22nd.

It is interesting to note in this context the mishna in Rosh Hashana that allows witnesses that see the new moon to get to the Bet Din even at the expense of chilul shabbat. This allowance is only for the months of Nissan and Tishrei in that they are the only ones that have a direct influence on the major festivals. We see that the very process of kidush hachodesh is controlled by the final product of the festivals in line with the comments of the sefer hachinuch.

Witnesses or a fixed calendar?

The standard explanation of the history of this mitzvah puts the stress on the witnessing of the new moon and the declaration by the Bet Din. Only after the dissolving of the Bet Din did we move to a system of a set calendar (in app. 359).

Rav Saadia Gaon has a different idea. He claims that the present system of a set calendar is the system that was given to Moshe at Sinai and it was only for a short period of time that the witnesses were used instead of the calendar. His position was questioned by virtually all of the rishonim, see for instance the Ibn Ezra in this weeks parsha, and some went as far to say that Rav Saadia himself didn't believe in this but rather used it in a polemic against the Kaarites.

Two middle position exist, that of the Rambam and that of Rav Hai Gaon that define two options of kidush hachodesh one by witnesses and one by calendar and there are various factors that control which one we use. (there are significant differences between them and this is a subject for a much larger treatment).

This debate as well, I think, has to do with the ambiguity of the mitzvah as well. The fact that the mitzvah is phrased in its "final stage" "this should be the first month" leads us to different positions as to how to arrive at the conclusion.

To sum up, we have seen two debates that seem to stem from the manner in which the mitzvah was phrased. This should be a point to look out for in the coming weeks as we encounter many other mitzvot that a careful reading of what the text says, and what it does not say can lead us to different and interesting definitions of the obligations.

Shabbat Shalom