1) DETERMINING THE YEAR OF THE "CHURBAN" AND THE YEAR OF "SHEMITAH"
QUESTION: The Gemara quotes Rav Huna brei d'Rav Yehoshua who teaches how to calculate the Shemitah based on the number of years that have passed since the destruction of the second Beis ha'Mikdash. As Rashi explains, the basis for the Gemara's calculation is the Gemara in Ta'anis (29a) which says that the year in which the Beis ha'Mikdash was destroyed was the year after Shemitah (that is, the first year of a new Shemitah cycle).
In what year was the second Beis ha'Mikdash destroyed? The TUR (CM 67) writes that according to the calculation of RASHI here, the year 5087 (1327 C.E.) was a Shemitah year. Extrapolating backwards, this means that the Beis ha'Mikdash was destroyed in the year 3828 (68 C.E.), and the preceding year was a Shemitah year. This is consistent with the dating of the Churban given by the Gemara here (see Chart).
This calculation is not unanimous, however. The Tur writes that according to the RI (see TOSFOS here), the Shemitah year occurred in the year 5088 (1328 C.E.). According to this figure, the Churban occurred in the year 3829 (69 C.E.), and the previous year (3828) was a Shemitah year.
The RAMBAM (Hilchos Shemitah 10:6) cites the broadly accepted tradition of the Ge'onim, according to which the year 4935 (1175 C.E.) was a Shemitah year. This means that the year 5089 (1329 C.E.) was a Shemitah year. Extrapolating backwards, this means that the Beis ha'Mikdash was destroyed in the year 3830 (70 C.E.), and the preceding year was a Shemitah year. This opinion is consistent with the current system of counting the Shemitah cycle (the most recent Shemitah years were 5761 and 5768, or 2001 and 2008 C.E.).
Why do the opinions vary with regard to the year in which the Beis ha'Mikdash was destroyed? The Gemara says explicitly that the Beis ha'Mikdash was destroyed in the year 3828 (68 C.E.)!
Moreover, how could the Churban have occurred in the year following a Shemitah year? The Beis ha'Mikdash stood for 420 years (a number divisible by 7), and, according to Rebbi Yehudah (whose opinion is accepted by the Gemara here and by the Halachah), the Shemitah year occurs every seven years (even after a Yovel year). Accordingly, since the Shemitos were counted from the time that the Jews returned to the land and rebuilt the second Beis ha'Mikdash (because the Kedushah of the land was annulled when the first Beis ha'Mikdash was destroyed), the year in which the Beis ha'Mikdash was destroyed should have been a Shemitah year, and not the year after a Shemitah year.
(a) RASHI explains that the Churban occurred 3828 years after the creation of the world. In response to the second question, Rashi explains that the Shemitah count did not begin immediately when the second Beis ha'Mikdash was built. Ezra arrived only six years after the construction began, and he re-sanctified the land with regard to counting the years of Shemitah and with regard to the other laws that depend on the Kedushah of the land.
(b) TOSFOS and the RASHBAM answer the second question by explaining that the Beis ha'Mikdash was destroyed 421 years, and not 420 years, after it was built. Accordingly, the year in which the Beis ha'Mikdash was destroyed indeed was the year that followed Shemitah (since, as mentioned above, the Shemitah count began when the Jews returned to the land and rebuilt the Beis ha'Mikdash, and 420 is divisible by seven).
Tosfos and the Rosh reject this approach because it cannot be reconciled with the Beraisa's calculation (beginning of 9a). The Beraisa states that the second Beis ha'Mikdash stood for 420 years.
The DERISHAH (CM 67:9) explains that the Beraisa earlier counts only full years when it says that the Beis ha'Mikdash stood for 420 years. The Beis ha'Mikdash continued to stand, however, for a number of months after 420 full years passed from the time it was rebuilt. The calculation that Rav Papa provides for determining how many years have passed since the Churban considers the year that the Beis ha'Mikdash was destroyed as being the year after the Churban, since "one day out of a year is counted as a year" (Rosh Hashanah 2b). However, the calculation for determining the Shemitah year is based on the number of full years after the Churban (or 420 years).
Others, such as the BA'AL HA'ME'OR, do not have the words, "add one year," in the Gemara's calculation. Hence, the calculation of Shemitah may also be computed by counting the year in which the Churban occurred as year one after the Churban, because of the months that remained in the year in which the Churban occurred. Since that year was the first year of a Shemitah cycle, the seventh year of that cycle and every seventh year henceforth will be a Shemitah year.
The Ba'al ha'Me'or suggests further that the calculation of the Gemara here does not involve the number of years that have passed since the Churban, but rather it is based on the number of years from the creation of the world. Accordingly, the Girsa of "add one year" is correct: if -- when one adds one to the number of years since creation passed -- that number is divisible by seven, then that year is a Shemitah year. Consequently, year 420 of the Beis ha'Mikdash (or 3828 from creation) was a Shemitah year, since adding one to that year equals a sum (3829) that is divisible by seven.
RABEINU TAM also dates the Churban at year 421 after the Beis ha'Mikdash was rebuilt. He reconciles the calculation of the Gemara based on another variant Girsa.
The RAMBAM (Hilchos Shemitah v'Yovel 10:4) sets the date of the Churban at year 420, as Rashi does. However, he explains that the Gemara in Ta'anis does not mean that the year of the Churban was the year after Shemitah, but rather that the year that began two months after the Churban was a year after Shemitah.
According to all of these opinions, the year 3828 was a Shemitah year, in contrast to Rashi's opinion.
(c) If the Rambam agrees with the Ri who says that year 420 of the second Beis ha'Mikdash was a Shemitah year, then why does he calculate the Shemitah year as being 5089, one year later than the Shemitah year that the Ri calculates?
The MAHARALBACH (#142, section 5, cited by the DERISHAH CM 67:9) addresses this question. He points out that there are two ways to count the years from the creation of the world. The years can be counted either from the day that Adam ha'Rishon was created (which was Rosh Hashanah, according to Rebbi Eliezer, whose opinion the Halachah follows; see Rosh Hashanah 12a and Insights there), or from the year before Adam ha'Rishon was created, by adding an extra year to the count. The reason an extra year is added is that the creation of the world actually started five days before the creation of Adam ha'Rishon, and part of a year is considered a year ("one day out of a year is counted as a year," Rosh Hashanah 2b). According to the opinion of Rebbi Yehoshua, Adam ha'Rishon was created in Nisan, which was a half a year before the first Rosh Hashanah, and thus there is even more of a reason to add one year to the count of years, rather than to begin the count at the first Rosh Hashanah. (For the purpose of calculating the Molad, it is also convenient to include the extra year.) This extra year is referred to as the "Shenas Tohu," the "year of nothingness," since the world -- for most of that year -- had not yet been created. It is also referred to as the year of "BaHaRaD," an acronym for the moment of the Molad of the Rosh Hashanah of the year prior to creation (based on extrapolating backwards in time) had the heavenly bodies been in existence at that time. ("BaHaRaD" stands for "Monday" (day two, or "Beis"), five hours ("Heh"), and 204 Chalakim ("Reish" and "Dalet") into the day.) The Molad for the following Rosh Hashanah (the first Rosh Hashanah of the world) was "V-Y-D" (this stands for Friday (day six, or "Vav"), at the end of the fourteenth hour ("Yud" and "Dalet") of the day; see TOSFOS to Rosh Hashanah 8a, DH li'Sekufos).
Our common count of years from creation includes the added year of "BaHaRaD." Does the Gemara's count of the years until the Churban of the Beis ha'Mikdash include that additional year? The Maharalbach asserts that it cannot include an extra year, since the Gemara's calculation is based directly on the number of years that Adam ha'Rishon and his descendants lived. Since Adam ha'Rishon was born on Rosh Hashanah of "V-Y-D," there is no reason to add an extra year to his age because of the year of "BaHaRaD." The Maharalbach points out that this is alluded to in the words of the Rambam (in Hilchos Shemitah v'Yovel 10:2), who contrasts the year of the creation of Adam ha'Rishon to the year from which the counting from creation begins. The Maharalbach proves that this is also the opinion of RAV SA'ADYAH GA'ON and RAV HAI GA'ON.
Accordingly, the Shemitah year which occurred 3828 years from the creation of Adam ha'Rishon actually occurred in the year 3829, according to our count of years. Even though the Rambam accepts the opinion of the Ri, nevertheless the correct date for the Shemitah year is 5089, and not 5088, because of the added year.
Does the Ri disagree with the calculation of the Rambam? The Maharalbach and the TASHBATZ (2:99) write that the Ri and the Rambam are in agreement. When the Tur writes that according to the Ri, Shemitah was in 5088 and, according to Rashi, it was in 5087, he is counting the number of years since the creation of Adam ha'Rishon, just like the count of the Gemara with regard to the Churban. (There indeed was a widely-held practice to count the year of creation in that manner among the Jews of Oriental countries, as the Maharalbach and the Ba'al ha'Me'or here mention. They would have counted the current year as 5769 and not 5770.) Therefore, the correct year of Shemitah according to our way of counting is 5089 according to the Ri, or 5088 according to Rashi. Consequently, the year given by the Ri is the same year as that given by the Rambam.
The TESHUVOS KOL MEVASER (1:60) does not accept the view of the Maharalbach. He asserts that according to Rashi and the Ri, the count of the Gemara which puts the year of the Churban at 3828 already includes the year of "BaHaRaD," since Adam ha'Rishon was created before the Molad of the Rosh Hashanah after creation (of "V-Y-D"). Thus, there indeed are three opinions with regard to the correct calculation of the Shemitah year. According to Rashi, Shemitah was in the year 5087, according to the Ri in 5088, and according to the Rambam in 5089.
HALACHAH: The ROSH (1:7) and the TUR (CM 67) rule like Rashi. However, the REMA (CM 67:1) and most Rishonim rule like Tosfos, who says that the Shemitah year was year 420 of the years of the second Beis ha'Mikdash. The Rambam (Hilchos Shemitah v'Yovel 10:6) writes that "it is well-known that in the times of the Ge'onim the people in Eretz Yisrael all observed the Shemitah year based on this calculation. This is the basis for current-day practice." (The Maharalbach writes that the reason why we do not observe multiple years in the seven-year cycle as Shemitah in order to fulfill all of the opinions is that, at present, Shemitah is d'Rabanan, and thus we are not Machmir.)