Torah Portion: Bo
This month shall be for you the beginning of the months, it shall be for you the first of the months of the year (Shemos 12:2).
It is a positive commandment to sanctify months and intercalate years at an [authorized] court—one that is great in wisdom, comprised of ordained judges, and that is located in the land of Israel—and to set the festivals of the year by that sanctification. Scripture thus says: This month shall be for you the beginning of the months; that is, when you see a renewal of the moon, set it as a new month. Or even if you do not see it but by the traditional reckoning it should have appeared, it is required to sanctify the month. Included in this commandment is the mitzvah of adding a leap month to the year [when necessary], for the underlying purpose of the sanctification of months is to enable Israel to keep the festivals of Hashem at their correct times, and the mitzvah of making leap years follows this principle.
The general scheme of the mitzvah is as follows: Two acceptable Israelites come before the court, and testify in front of them that they saw the moon at its renewal, and the judges proclaim the new month based on their testimony by declaring: “Today is sanctified.”
And if you ask, if so, how do we sanctify months or make leap years nowadays—after all, we do not have ordained sages anymore? Know that we have a tradition that it was R’ Hillel Ha-Nasi, son of R’ Yehudah Ha-Nasi, who was great in his generation and was ordained in the Land [of Israel], who was the Sage who instituted the reckoning of leap years and it was he who sanctified all the months and intercalated all the years to come until the coming of Eliyahu, and it is upon that which we rely upon today.
Among the roots of this commandment: It is to enable Israel to keep Hashem’s festivals at their correct times, for Hashem commanded to keep Passover when it is spring for the wheat, and Sukkos at the time of the harvest, and if not for leap years, these festivals would come at times other than these. This is so because Israel reckons their months and their festivals by the days of the moon, [and twelve lunar months] is shorter than a solar year by ten days. Now, the ripening of grains and other produce happens through the power of the sun; therefore, if we would not adjust the lunar-based years to the solar-based years, Passover would not come in the springtime and Sukkos would not fall at harvest time.
This commandment applies in all places and at all times when we have ordained sages and the above-mentioned conditions are present. One who neglects this and does not perform [this sanctification]—if he is a sage worthy of doing it—violates a positive commandment and his punishment is very severe, for he causes an upset in the proper times of the festivals. But currently, when, because of our sins, we do not intercalate years through sages, our reckoning relies on accepted tradition from R’ Hillel, as we have said.