We continue with Maseches Rosh Hashanah, Chapter 1, Mishnah 4. This mishnah deals with the permission granted to the witnesses of the new moon to desecrate Shabbos in order to reach the court, with the question of for which months this permission was given, and with its reason.
The text of the Mishnah:
"Al shnei chodashim mechallelin es haShabbos: al Nisan v'al Tishrei, shebahen hashluchin yotz'in l'Surya, uvahen mesaknin es hamo'ados. Ukeshehayah Beis HaMikdash kayam - mechallelin af al kulan, mipnei takanas hakorban".
Explanation of the Mishnah:
The witnesses who saw the new moon were permitted to desecrate Shabbos if this was necessary in order to reach the court in time, so that the court could establish the thirtieth day as the first day of the coming month. By Torah law they were permitted to desecrate Shabbos for all the months of the year, but the Sages limited the permission to two months only: Nisan and Tishrei.
The Mishnah gives two reasons for the special status of these months:
"Shebahen hashluchin yotz'in l'Surya" - these are the months in which the messengers went out to inform the Jews of the diaspora about the fixing of the month.
"Uvahen mesaknin es hamo'ados" - in these months the festivals are set: Pesach in Nisan, and Yom Kippur and Sukkos in Tishrei. For this reason they were careful to allow Shabbos to be desecrated for them, in order to make certain that the festivals would be fixed on their proper dates.
"Ukeshehayah Beis HaMikdash kayam - mechallelin af al kulan" - when the Beis HaMikdash stood, the witnesses would desecrate Shabbos for all the months of the year, "mipnei takanas hakorban" - so that the Rosh Chodesh offering would be brought properly on its day, the true day of Rosh Chodesh.
The Gemara's question:
The Gemara points out that the first reason, the messengers going out to Syria, cannot be the true reason. For as we learned in the previous mishnah, the messengers would go out in six months of the year, and not only in Nisan and Tishrei.
There is, however, a difference between the way they went out in these two months and the way they went out in the rest of the months of the year: in the other months the messengers would set out once it became clear that the month was going to be sanctified the next day, even though they had not heard the court declare it Rosh Chodesh. But in Nisan and Tishrei, where complete certainty was required, they would not set out until they had actually heard the sanctification of the month.
Even so the Gemara asks: the messengers of the court themselves do not desecrate Shabbos. If so, their departure is no proof for permitting the witnesses to desecrate Shabbos - why should the witnesses desecrate Shabbos because of the departure of the messengers? From here the Gemara concludes that the primary reason for desecrating Shabbos in these two months is the proper fixing of the festivals: because in these months the festivals are set, and not because the messengers go out in them.
In summary: In this mishnah we learned that the Sages limited the permission for the witnesses of the new moon to desecrate Shabbos to two months only - Nisan and Tishrei, and gave two reasons for this: the departure of the messengers to Syria and the fixing of the festivals. The Gemara concluded that the primary reason is the proper fixing of the festivals, since the messengers themselves do not desecrate Shabbos. We also learned that when the Beis HaMikdash stood the permission was extended to all the months of the year, because of the proper offering of the korban.