1) "TOSEFES KEDUSHAH" -- ADDING TO A SANCTIFIED TIME
QUESTION: The Gemara records a Beraisa in which Rebbi Akiva derives the requirement of Tosefes Kedushah (the requirement to refrain from plowing and harvesting, Charishah and Ketzirah, before the Shemitah year begins) from the verse, "b'Charish uv'Katzir Tishbos" -- "You shall rest from plowing and harvesting" (Shemos 34:21). Rebbi Yishmael disagrees with Rebbi Akiva and derives the requirement to add to a sanctified time from the verse which teaches the Mitzvah to fast on Yom Kippur: "You shall afflict yourselves on the ninth of the month in the evening, from evening to evening, you shall rest on your day of rest" (Vayikra 23:32). Rebbi Yishmael points out that the verse first says to fast "on the ninth of the month," and then it says "in the evening," which means the tenth. Rebbi Yishmael understands that the verse means that one must add some time to the sanctity of Yom Kippur from the preceding day. Similarly, the other apparently extra phrases ("you shall rest" and "on your day of rest") teach that one must add to Shabbos and to other sanctified times, such as Yom Tov and the Shemitah year.
The Gemara explains that Rebbi Akiva needs no verse to teach Tosefes Kedushah for Yom Kippur because he derives that requirement from the verse with regard to Shemitah. Instead, Rebbi Akiva derives from the verse of Yom Kippur the obligation to eat on the ninth of Tishrei (see following Insight).
The Gemara's assertion that Rebbi Akiva needs no verse to teach Tosefes Kedushah for Yom Kippur is difficult to understand. The laws of Shemitah teach that there is an obligation of Tosefes Kedushah with regard to the prohibition of plowing and harvesting during the seventh year. However, this law cannot be the source for the requirement to add to the affliction of Yom Kippur and to the Isur Melachah of Shabbos and Yom Kippur (which includes 39 categories of Melachah). The obligation of Tosefes for affliction and Melachah cannot be derived through a "Binyan Av" from Shemitah because the prohibitions of plowing and harvesting apply more frequently than the prohibitions of affliction and 39 categories of Melachah (since they apply to Shemitah as well as to Shabbos, Yom Tov, and Yom Kippur). (The Gemara in Yoma (81a) presents a similar argument to refute a Kal v'Chomer with regard to affliction and Melachah.) Accordingly, Rebbi Akiva needs the Yom Kippur verse (Vayikra 23:32) to teach the requirement of Tosefes for Yom Kippur and Shabbos. Why is the Gemara so certain that Rebbi Akiva uses the verse for a completely different teaching? (REBBI AKIVA EIGER in GILYON HA'SHAS)
ANSWERS:
(a) The BA'AL HA'ME'OR and RASHBA prove from the Gemara in Moed Katan (4a) that even Rebbi Yishmael has another source for Tosefes Shevi'is: a Halachah l'Moshe mi'Sinai. However, neither he nor Rebbi Akiva learn the laws of Tosefes Shabbos, Yom Tov, and Yom Kippur from the laws from Shevi'is.
Based on the Gemara in Moed Katan, the Ba'al ha'Me'or and Rashba conclude (as Rebbi Akiva Eiger suggests) that the laws of Tosefes Shabbos, Yom Tov, and Yom Kippur indeed cannot be derived from Tosefes Shevi'is. Therefore, both Rebbi Yishmael and Rebbi Akiva must learn these laws of Tosefes from the verse which discusses Yom Kippur.
According to the Ba'al ha'Me'or, when the Gemara asked what Rebbi Akiva learns from the Yom Kippur verse, it could have answered that the verse is needed to teach Tosefes Shabbos, Yom Tov, and Yom Kippur. When it answers that the verse teaches the obligation to eat on the day before Yom Kippur, it is only "l'Ravcha d'Milsa" -- "for good measure."
(b) The RASHASH suggests that Rebbi Akiva cannot learn the laws of Tosefes Shabbos and Yom Kippur from Tosefes Shevi'is, as Rebbi Akiva Eiger asks. Rather, the laws of Tosefes Shabbos and Yom Kippur can be derived from a verse quoted in Yoma (81a, and Rashi to 81b, DH v'Tana d'Etzem Etzem). That verse may serve as Rebbi Akiva's source for the laws of Tosefes Shabbos and Yom Kippur (but it cannot serve as Rebbi Yishmael's source because it does not discuss Tosefes Shevi'is.)
This approach, however, raises the question: why does the Gemara say that Rebbi Akiva's source for the laws of Tosefes Shabbos and Yom Kippur is the verse quoted in Yoma (anonymously) and not the verse which discusses Yom Kippur?
(c) Perhaps the answer to Rebbi Akiva Eiger's question depends on the nature of the principle of "Tosefes." The prohibitions created by the law of Tosefes Kedushah may be viewed as independent prohibitions of "Tosefes" which apply immediately before the start of Shabbos but are not part of the prohibitions of Shabbos day, and not as an extension of "Shabbos" which causes them to apply earlier and stay in effect later. Alternatively, perhaps Tosefes Kedushah originates from the Kedushah to which it adds. That is, it extends the actual Kedushah of Shabbos to before the day actually begins.
Rebbi Akiva Eiger seems to understand that Tosefes Shabbos is a separate prohibition that applies Erev Shabbos and is not an extension of the ordinary prohibitions of Shabbos. Accordingly, Tosefes Shabbos can be derived from Tosefes Shevi'is only if the Isurim of Shabbos are comparable to the Isurim of Shevi'is. The law derived from Shevi'is could be stated as follows: "If the Isur Melachah of Shevi'is is preceded and followed by an Isur Melachah, so, too, the Isur Melachah of Shabbos and the Isur Achilah of Yom Kippur must be preceded and followed by an Isur Melachah or Isur Achilah." This is not a correct comparison, though, as Rebbi Akiva Eiger points out, because the Isur Achilah is more lenient than other Isurim since it applies less frequently.
If, however, the principle of Tosefes is considered an extension of the Kedushas ha'Yom of Shabbos, Yom Tov, and Shevi'is, then the law may be derived from Shevi'is as follows: "If the Kedushah of Shevi'is, which is a weaker Kedushah (it is not an Isur Kares), extends before and after Shevi'is, then certainly the Kedushos of Shabbos and Yom Kippur should extend before and afterwards." The focus is not on the Isurim but on the Kedushah, and the Kedushah of Yom Kippur (which prohibits both Melachah and eating) is certainly more stringent than the Kedushah of Shevi'is. The Gemara's comparison between Tosefes Shevi'is and the other Tosefos is clear.
Why does Rebbi Akiva Eiger maintain that Tosefes is not an extension of the Kedushah but rather a separate, independent Isur?
Rebbi Akiva Eiger may have inferred this way of understanding from RABEINU TAM's statement (9b, DH u'Mutar, cited by Rebbi Akiva Eiger here) that Tosefes Shevi'is before the actual year of Shevi'is does not apply to all of the laws of Shevi'is. It applies only to plowing and harvesting, but not to planting. Accordingly, it cannot be an extension of Kedushas Shevi'is, for if it was an extension of Kedushas Shevi'is it would prohibit even planting.
However, this reasoning alone is not sufficient to dismiss the answer to Rebbi Akiva Eiger's question. Rabeinu Tam there follows his own opinion as cited by Tosfos (DH v'Rebbi) that the Sugya here derives the requirement to add Tosefes to Shabbos and Yom Kippur at the end of the day from the requirement to add Tosefes to Shevi'is at the end of the year, and it is not discussing the Tosefes before Shabbos or Shevi'is. The Tosefes added after Shevi'is certainly appears to be an extension of the Kedushah of Shevi'is, because it requires that grain which grew at least one-third of its eventual growth during Shevi'is be treated like produce of Shevi'is even though it is harvested after Shevi'is (see Rashi and Tosfos DH u'Ketzir). Moreover, according to Rabeinu Tam, even the Tosefes at the start of Shevi'is seems to be an extension of the Kedushah of Shevi'is; it does not apply to the Isur of planting merely because of a technical reason (since there is no Isur of planting during Tosefes Shevi'is after Shevi'is, the requirement of Tosefes does not prohibit planting before Shevi'is either).
Alternatively, Rebbi Akiva Eiger's source for his view that Tosefes is not an extension of the original Kedushah of the day is the Gemara in Yoma (81a) which teaches that during Tosefes Shabbos the Lo Ta'aseh against performing Melachah on Shabbos and Yom Tov, and the punishment of Kares for performing Melachah on Shabbos and for eating on Yom Kippur, do not apply. According to the Gemara there, Tosefes is a new Isur which is appended to the beginning and end of the day.
This proof, however, may also be refuted. The Gemara there cites verses which teach that the Lo Ta'aseh and Kares do not apply during the period of Tosefes Shabbos and Tosefes Yom Kippur. This implies that Tosefes is an extension of the Kedushah of the day which the Torah "downgraded" to a Mitzvas Aseh, and it is not a new, independent Isur. (This concept is called "ha'Kasuv Nitko l'Aseh"; see Yevamos 11a.)
If this indeed is Rebbi Akiva Eiger's intention, he is consistent with his own opinion expressed elsewhere. In his TESHUVOS (3:80), Rebbi Akiva Eiger discusses why the Gemara in Sukah (28b) implies that women would be obligated to observe Tosefes Yom Kippur even without an explicit source. He asks that perhaps Tosefes Yom Kippur is considered a "Mitzvas Aseh sheha'Zeman Gerama," a Mitzvah which depends on a specific time period, from which a woman is exempt. If Tosefes is an extension of the Kedushah of the day itself, it should not be considered a "Mitzvas Aseh sheha'Zeman Gerama" because the requirement to observe the laws of Shabbos or Yom Tov itself is not considered a "Mitzvas Aseh sheha'Zeman Gerama." The Tosefes of the day should be identical to the laws of the day in every respect (except the severity of the Isur). A woman is obligated to observe the laws of the day because they are not positive commandments but negative ones. (See also KOVETZ SHI'URIM, Pesachim #212, who points out that the question of whether Tosefes is an extension of the original Kedushah or a new Isur may be the subject of debate between the Ba'alei ha'Tosfos in various places.)
2) THE OBLIGATION TO EAT ON EREV YOM KIPPUR
QUESTION: The Gemara derives from verses that one who eats and drinks on the ninth of Tishrei, the day before Yom Kippur, is considered as though he fasts on both the ninth and the tenth.
Why should eating on Erev Yom Kippur be considered like fasting?
ANSWERS:
(a) RASHI (DH Kol ha'Ochel) explains that by eating and drinking on the day before Yom Kippur one prepares himself for the fast. Since it is in preparation for the fast of the tenth, his eating is considered to be a part of his fasting. This is also the opinion of the ROSH (Yoma 8:22), and support can be found for it in the Yerushalmi.
(Rashi here and in Pesachim (68b), however, makes no mention of the aspect of preparation for the fast of the tenth. Rather, he explains that just as the Torah commands one to fast on the tenth, the Torah also commands one to eat on the ninth. The Mitzvah to eat on the ninth is not related (to such an extent) to the requirement to fast on the tenth. This variation in the explanations of Rashi in the different places where this statement of the Gemara appears may be based on the context of the different Sugyos in those Gemaros, as explained by RAV YAAKOV D. HOMNICK in SEFER MARBEH SHALOM #30.)
(b) The SHIBOLEI HA'LEKET, in the name of RABEINU YESHAYAH, says that it is especially difficult to fast after one has eaten and drunk a lot on the day before the fast. Therefore, one is rewarded for eating on the ninth as if he lengthened his fast of the tenth. (Support for this understanding can be adduced from the Gemara in Ta'anis (26a) which says that fast-days are not established on Sundays, for it is too difficult to fast after a day of festivity. See Pardes Yosef, Vayikra.)
(c) The TUR (OC 604) quotes a story from the Midrash of a simple Jew who outbid the king's officer to buy a fish on the day before Yom Kippur. The Jew later explained to the king that he wanted the fish "to celebrate that Hash-m is going to pardon the sins of the Jewish people" the next day. This demonstrates that eating on the day before Yom Kippur shows one's faith that the fast of the following day will earn him a complete pardon. RABEINU YONAH (Sha'arei Teshuvah 4:8) also suggests such an explanation.
(d) Since Yom Kippur is a Yom Tov, it requires a Se'udas Yom Tov, a festive meal. However, one cannot have a Se'udah on Yom Kippur because of the obligation to fast. The Se'udah, therefore, was moved to the ninth. Since the Se'udah of the ninth is part of the celebration of the tenth, one who eats on the ninth is considered to have fasted on both days. (Rabeinu Yonah, Sha'arei Teshuvah 4:9)
(e) The ARUCH LA'NER (Rosh Hashanah 9a) suggests a novel approach. During the year, a person sins with both his body and his soul. One who fasts on Yom Kippur afflicts his body in order to attain atonement for the sins he committed with his body against his soul. When he eats on the day before Yom Kippur, he afflicts his soul in order to atone for the sins he committed with his soul against his body (such as excessive fasting on days when one is not required to fast).
All of these reasons assume that the Mitzvah to eat on the ninth of Tishrei is related to the fast of atonement on the tenth. Consequently, one may conclude that women are also obligated to eat on the ninth of Tishrei, even though it is a time-dependent obligation from which women are normally exempt. Since women must fast on Yom Kippur, they are also required to do everything connected with that fast, which should include eating on the ninth. This is how the MAHARIL rules as cited by the DARCHEI MOSHE (OC 604:1). (See also REBBI AKIVA EIGER, Teshuvos 1:16, and KESAV SOFER, Teshuvos OC 112).

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