1. All the statements made previously regarding the [prerogative to] sanctify Rosh Chodesh because of the sighting of the moon, and [to] establish a leap year to reconcile the calendar or because of a necessity, apply to the Sanhedrin in Eretz Yisrael. [For it is they] alone, or a court of judges possessing semichah that holds sessions in Eretz Yisrael and that was granted authority by the Sanhedrin, [who may authorize these decisions].¹The Ramban [in his gloss on Sefer HaMitzvot (Positive Commandment 153)] differs and explains that although it was necessary for the judges who established the calendar to have semichah, there was no necessity that this function be carried out by the Sanhedrin or a court deputized by it.

[This concept is derived] from the command given Moses and Aaron [Exodus 12:2]: "This month shall be for you the first of months" The Oral Tradition as passed down, teacher to student, from Moses our teacher [throughout the generations, explains that] the verse is interpreted as follows:²This explanation was recorded for posterity in Rosh HaShanah 21b. This testimony is entrusted to you and those [sages] who arise after you and who function in your position.³I.e., to the Sages of the Sanhedrin, who preserve the tradition of the Jewish court as initiated by Moses and Aaron.

When, however, there is no Sanhedrin in Eretz Yisrael, we establish the monthly calendar and institute leap years solely according to the fixed calendar that is followed now.

2. This concept is a halachah communicated to Moses on [Mount] Sinai:⁴In the Introduction to his Commentary on the Mishnah, the Rambam defines a halachah communicated to Moses on [Mount] Sinai as a law that is neither explicitly stated nor alluded to in the Written Law, but communicated through the Oral Tradition.

See also the statements of the Ramban (loc. cit.), who objects to the Rambam's statements, and asks which source states that this is a halachah communicated to Moses on Mount Sinai. When there is a Sanhedrin, the monthly calendar is established according to the sighting of the moon. When there is no Sanhedrin, the monthly calendar is established according to the fixed calendar that we follow now, and the sighting of the moon is of no consequence.

When the fixed calendar is followed, there are times when the day established [as Rosh Chodesh] will be the day on which the moon is sighted, and there are times when the sighting will either precede or follow it by a day.⁵As explained in Chapter 6, the fixed calendar is based on the mean motion of the sun and the moon - i.e., their average rate of progress in the heavens. As explained in Chapter 11 onwards, the progress of the sun, and to an even greater extent that of the moon, deviates from this mean from time to time. Although ultimately these deviations will balance out, at any given time the day established as Rosh Chodesh may be before or after the day on which the moon can be sighted. It is, however, an extremely extraordinary phenomenon for [the day established as Rosh Chodesh] to be a day after the sighting [of the moon], [and this is possible only] in the lands that are west of Eretz Yisrael.⁶As explained in Chapter 18, Halachah 13, in the lands west of Eretz Yisrael the moon is sighted earlier than in Eretz Yisrael.

3. When did the entire Jewish people begin using this calendar? At the conclusion of the Talmudic period, when Eretz Yisrael was in ruin, and an established court no longer remained there.⁷Based on the Rambam's statements in Sefer HaMitzvot (loc. cit.), the Chatam Sofer (Yoreh De'ah, Responsum 234) explains that the Rambam's intent is that, from that time onward, a formal court no longer held sessions in Eretz Yisrael; the land, however, remained populated by Jews. (See the notes on Halachah 5.) In the era of the Sages of the Mishnah, and in the era of the Sages of the Gemara until the time of Abbaye and Ravvah,⁸This concept is derived from Rosh HaShanah 21a, which states that Ravvah fasted two days on Yom Kippur, because he did not know which day was established by the court in Eretz Yisrael. [the people] would rely on the establishment [of the calendar] in Eretz Yisrael.⁹This refers to the establishment of the fixed calendar by Rabbi Hillel (Hillel II), approximately two generations after the composition of the Jerusalem Talmud.

Most commentaries assume that the Rambam's intent is that until the time of Rabbi Hillel (not Hillel the Great, but a descendant of his, who lived several hundred years afterwards), the court sanctified the moon based on the testimony of witnesses. Rav Kapach objects to this interpretation, noting that the sanctification of the moon required judges with semichah, and it appears that the practice of semichah had been nullified prior to this time.

Noting the precise words used by the Rambam, "[The people] would rely on the establishment [of the calendar] in Eretz Yisrael," Rav Kapach explains that the sanctification of the moon based on the testimony of witnesses had ended several generations previously, with the cessation of the practice of semichah. Nevertheless, the international Jewish community would look to the court in Eretz Yisrael for the establishment of the calendar. For the family of the Nesi'im had a private tradition regarding the calculation of the calendar. Nevertheless, at the time of Rabbi Hillel, this practice was also discontinued, and a fixed calendar was established that did not require the authority of any particular court.

4. When the Sanhedrin functioned and the calendar was established based on the sighting [of the moon], the inhabitants of Eretz Yisrael and, [similarly, the inhabitants of] all the places where the messengers of Tishrei¹⁰See Chapter 3, Halachot 11-13. would arrive, would celebrate the holidays for one day only.

The inhabitants of the distant places that were not reached by the messengers of Tishrei would celebrate two days because of the doubt involved. For they did not know the day that the inhabitants of Eretz Yisrael established as [the beginning of] the new month.

5. In the present era, when the Sanhedrin no longer exists, and the court of Eretz Yisrael establishes [the months] according to the [fixed] calendar,¹¹Implicit in the Rambam's words is a concept explained in greater detail in Halachah 13: The determination of the calendar depends on the establishment of the calendar by the court in Eretz Yisrael. according to law, it would be appropriate for [Jews] throughout the world to celebrate the holidays for one day alone.¹²As prescribed by the Torah. Once the date on which the festivals should be celebrated could be universally known because of the fixed calendar, the safeguard of celebrating the holidays for two days was no longer necessary. For [the inhabitants of] the distant regions of the diaspora and the inhabitants of Eretz Yisrael rely on the same [fixed] calendar and establish [the festivals] accordingly. Nevertheless, the Sages ordained [that the inhabitants of the diaspora] retain the custom of their ancestors.¹³Beitzah 4b explains that this rule was ordained lest the gentile authorities oppress the Jewish people and prevent the inhabitants of the diaspora from communicating the tradition of the calendar to their descendants. They would then have to rely on information conveyed from Eretz Yisrael again.

6. Therefore, [the inhabitants of] all the places that the messengers of Tishrei would not reach in the era when the messengers were sent out should celebrate two days even in the present era, just as they did when the inhabitants of Eretz Yisrael established [the calendar] according to the sighting of the moon.

In the present era, the inhabitants of Eretz Yisrael continue their custom and celebrate one day;¹⁴See, however, Halachot 11 and 12. for they never celebrated two days. Thus, our celebration of the second day of the holidays in the diaspora at present is a Rabbinic institution.¹⁵I.e., originally, the second day of the holidays was observed because of the doubt of the day on which to observe the Torah's commandment. In the present era there is no longer any doubt, and the observance of the second day of a holiday has the status of a Rabbinic ordinance.

7. [Even] when the calendar was established based on the sighting of the moon, the majority of the inhabitants of Eretz Yisrael would celebrate Rosh HaShanah for two days, because of the doubt involved.¹⁶To explain: Generally, the court would endeavor to structure the calendar so that the moon would be sighted on the thirtieth night of Elul. In expectation of the probability that the following day would be declared Rosh HaShanah, the people would observe all the holiday prohibitions and sound the shofar on the thirtieth day. Nevertheless, since it was possible that the moon had not been sighted, the people outside the immediate surroundings of Jerusalem would observe the following day as well.

See the Jerusalem Talmud (Eruvin 3:9) which states that the observance of Rosh HaShanah for two days was ordained by "the prophets of the earlier generations." Sotah 48b states that this term refers to the prophets of the First Temple era. They would not know the day on which the court established the new month, because the messengers would not depart on the holiday.¹⁷See Chapter 3, Halachah 8.

8. Moreover, even in Jerusalem, where the court would hold session, there were many times when the holiday of Rosh HaShanah was celebrated for two days. For if witnesses did not arrive on the thirtieth day [following Rosh Chodesh Elul], the day on which they had awaited [the arrival of] witnesses would be regarded as holy,¹⁸As mentioned above, except for the offering of the Rosh HaShanah sacrifices, the thirtieth day following Rosh Chodesh Elul was always observed as Rosh HaShanah in expectation of the arrival of witnesses. and the following day would be regarded as holy.¹⁹For it would actually be observed as Rosh HaShanah.

Since [there were times when] they would observe [Rosh HaShanah for] two days even when they sanctified the months according to the sighting [of the moon], [our Sages] ordained that even the inhabitants of Eretz Yisrael²⁰Including even the inhabitants of Jerusalem. should always celebrate [Rosh HaShanah] for two days in the present era, when [the holidays] are established based on the fixed calendar. Thus, even [the observance of] the second day of Rosh HaShanah in the present era is a Rabbinic ordinance.

9. The celebration of the holidays for one or two days is not dependent on geographic distance [alone]. What is implied?

If a place is located within a five-day - or less - journey from Jerusalem, and thus it was surely possible for the messengers to reach them, we do not postulate that the inhabitants celebrate only one day. For we have no way of knowing whether or not the messengers [of the High Court] would journey to this place.²¹As the Rambam continues to explain, the determining factor is not the geographic distance of a place from Jerusalem, but rather the custom followed in this place at the time when the High Court sent out messengers. Perhaps the messengers did not journey to this place because it was not populated by Jews at that time. [And if] it became populated by Jews after it [had become customary] to establish [the festivals] according to the fixed calendar, they [would be] obligated to celebrate two days.

Alternatively, [perhaps the messengers did not reach there,] because there was a blockade on the way, as existed between Jerusalem and the Galilee during the time of the Mishnah,²²See Bava Batra 38a and Ketubot 17b, which tell of a time when a blockade prevented communication between Jerusalem and the Galilee. or perhaps the Samaritans would prevent the messengers from passing through their [territory].

10. If the matter were dependent on geographic distance alone, all the inhabitants of Egypt would observe the holidays for only one day, for it is possible for the messengers of Tishrei to reach them. The distance between Jerusalem and Egypt via Ashkelon is a journey of eight days or less. Similar concepts apply regarding the majority of Syria. One thus can conclude that the matter is not dependent solely on geographic distance.

11. Thus, the principles governing this matter can be summarized as follows: Whenever the distance between Jerusalem and a particular place exceeds a ten-day journey, the inhabitants should observe [the holidays] for two days, as was their previous custom. For the messengers sent out for Tishrei [cannot be guaranteed] to reach places other than those within a ten-day journey from Jerusalem.²³For the messengers were forbidden to travel on Rosh HaShanah, Yom Kippur, and the two Sabbaths between Rosh HaShanah and Sukkot. In the years when Rosh HaShanah is observed on the Sabbath, the messengers could proceed a further day. Nevertheless, since this is not so in the majority of the years, a ten-day journey is accepted as the standard measure.

[The following rules apply when, by contrast,] places are a ten-day journey or less from Jerusalem, and thus it is possible that the messengers could have reached them: We see whether that place is [located in the portions of] Eretz Yisrael that were inhabited by Jews during the time the calendar was established on the basis of the sighting [of the moon] during the second conquest [of the land] - e.g., Usha, Shefaram, Luz, Yavneh, Nov, Tiberias, and the like. [The inhabitants of these places] should celebrate only one day.

If the place is part of Syria²⁴Note Hilchot Terumah 1:3, which defines Syria as referring to lands conquered by King David before the entire territory of Eretz Yisrael proper had been conquered. Therefore, it was not considered part of the Holy Land with regard to most ritual questions according to the Torah itself. Nevertheless, the Rabbis extended many of the laws applying to Eretz Yisrael to this territory as well. - e.g., Tyre, Damascus, Ashkelon,²⁵The inclusion of Ashkelon, which is located to the southwest of Eretz Yisrael, in Syria clearly indicates that the Rambam is referring to the halachic conception of the latter term, and not the geographic one, since Syria is to the northeast of Eretz Yisrael.

There is, however, a slight difficulty with the Rambam's statements: In Hilchot Terumah 1:9, he describes Ashkelon as being part of the diaspora.and the like - they should follow the custom of their ancestors. If [the custom was to celebrate] one day, [they should celebrate] one day. [If the custom was] two days, [they should celebrate] two days.

12. When a place is located within a journey of ten days or less from Jerusalem, and it is part of Syria or the diaspora, and [its inhabitants] have no [established] custom conveyed [from previous generations], they should celebrate two days, as is customary in the world at large. [The same rules apply to] a city that was created in the desert of Eretz Yisrael, or a city first populated by Jews in the present era.²⁶Based on this halachah, according to the Rambam, most Jews living in Eretz Yisrael today should celebrate the holidays for two days. Indeed, the Eretz Tzvi, a text that documents the prevailing customs in Eretz Yisrael before the waves of European immigration, states that in cities like Ramlah, that did not have an existing custom dating back to the Talmudic period, the holidays would be celebrated for two days, as the Rambam states.

It was not until the resettlement of Eretz Yisrael in the present era that such cities began observing the holidays for only one day. The source for this practice is the commentary of the Ritba (Rosh HaShanah 16b), who states that, in the present era, it is the geographic definitions of Eretz Yisrael and the diaspora that determine whether or not one should celebrate one day.

[It must be emphasized that even according to the Ritba, it is questionable whether the inhabitants of areas of the Negev below Beersheba should celebrate the holidays for only one day. For these places are also beyond the geographic limits of Eretz Yisrael of the Talmudic period.]

[At present,] the celebration of the second day of a holiday is always a Rabbinic institution. This applies even to the celebration of the second day of Rosh HaShanah, which is observed by all Jews in the present era.

13. The calculations that we follow in the present era, every individual in his community, to ascertain which day is Rosh Chodesh and which day is Rosh HaShanah, do not determine [the calendar], nor do we rely on these calculations. For we do not institute leap years or establish the monthly calendar in the diaspora. We rely on the calculations of the inhabitants of Eretz Yisrael and their establishment of the calendar.

The reason we make calculations is merely for the sake of information. For we know that the inhabitants of Eretz Yisrael rely on the same calendar. Thus, our calculations are intended to determine the day that the inhabitants of Eretz Yisrael establish as Rosh Chodesh or a festival. For it is the establishment of the calendar by the inhabitants of Eretz Yisrael that establishes a day as Rosh Chodesh or a festival, not our calculations of the calendar.²⁷The Rambam's statements in this halachah are a reiteration of the principles he expresses in Sefer HaMitzvot, loc. cit. Citing Isaiah 2:3, "Out of Zion shall come forth the Torah," the Rambam emphasizes that the determination of the calendar is solely the province of the inhabitants of Eretz Yisrael.

Until the time of Rabbi Hillel, the court of Eretz Yisrael determined the calendar through their independent calculations. Even after the court ceased to function and the fixed calendar was adopted, the determination of the calendar still depends on the establishment of the calendar in Eretz Yisrael. The only difference is that from the time of Rabbi Hillel onward, instead of determining the calendar independently, the inhabitants of Eretz Yisrael would rely on the fixed calendar.

For this reason, the Rambam points to a Divine covenant insuring that there will always be Jews living in our Holy Land. For were there not to be any Jews living in Eretz Yisrael, heaven forbid, we would not be able to determine the calendar. (See Chatam Sofer, Yoreh De'ah, Responsum 234).