1) LEARNING A SINGLE LAW FROM BOTH A VERSE AND A HALACHAH L'MOSHE MI'SINAI
QUESTION: Rebbi Akiva derives from the verse, "b'Charish uva'Katzir Tishbos" -- "You shall cease from all plowing and reaping" (Shemos 34:21), the law of Tosefes Shevi'is, the obligation to refrain from working the land for some time before the seventh year begins and after it ends. The Gemara questions why Rebbi Akiva needs a verse to teach the law of Tosefes Shevi'is when this law is taught by a Halachah l'Moshe mi'Sinai. The Halachah l'Moshe mi'Sinai of "Eser Neti'os" states that one is permitted to plow beneath young plantlings under certain circumstances until Rosh Hashanah of the seventh year. This law implies that plowing beneath fully-grown trees is prohibited even before Rosh Hashanah arrives because of Tosefes Shevi'is. Why, then, does Rebbi Akiva need a verse to teach the law of Tosefes Shevi'is?
The Gemara's question is difficult to understand. While it is true that the obligation of Tosefes Shevi'is is derived from the Halachah l'Moshe mi'Sinai, if the Halachah l'Moshe mi'Sinai would be the only source, the law of Tosefes Shevi'is would not have the status of a law written explicitly in the Torah but rather the status of a Halachah l'Moshe mi'Sinai (which differs from a law written explicitly in the Torah). The RAMBAM (Perush ha'Mishnayos to Mikva'os 6:7) writes that although a Halachah l'Moshe mi'Sinai is mid'Oraisa, it is considered "Divrei Sofrim" and one may be lenient in the case of a doubt. The Torah explicitly writes a certain Halachah even though it is also taught as a Halachah l'Moshe mi'Sinai in order to give it the status of a law written explicitly in the Torah. Accordingly, it is obvious why the verse teaches the law of Tosefes Shevi'is even though it is a Halachah l'Moshe mi'Sinai. What is the Gemara's question?
The Gemara itself expresses this reasoning (in Temurah 18a). The Gemara says that although there is a Halachah l'Moshe mi'Sinai which teaches that the Temurah of a Korban Asham may not be offered as a Korban, a verse is needed to teach that one transgresses a Mitzvas Aseh if he actually offers it. (MATZEVES MOSHE)
ANSWER: The MATZEVES MOSHE answers that the intention of the Gemara's question is as follows. The Gemara in numerous places states that when there are two ways to interpret a verse and one of those ways would establish a second prohibition (Lo Ta'aseh) for an act which is already prohibited by a Lo Ta'aseh, it is preferable not to interpret the verse as teaching a second Lo Ta'aseh (see Pesachim 24b, Bechoros 6b). It is more logical that the verse's intention is to teach a new Halachah rather than to strengthen the existing prohibition by adding another Lo Ta'aseh.
The Gemara's question on the statement of Rebbi Akiva is based on this principle. The verse, "You shall cease from all plowing and reaping," may be understood in one of two ways: it refers either to the laws of Shevi'is or to the laws of Shabbos (as Rebbi Yishmael understands it). Rebbi Akiva understands that the verse teaches the law of Tosefes Shevi'is, which is a prohibition which is already known from the Halachah l'Moshe mi'Sinai. Since Rebbi Akiva could have interpreted the verse in another way -- that it permits Ketzirah on Shabbos for the sake of the Mitzvah of the Omer offering on Shabbos, as Rebbi Yishmael interprets the verse -- why does he explain that it teaches a law which is already known and that it merely adds severity to the prohibition of Tosefes Shevi'is? It is more logical that the verse's intention is to teach a new Halachah! This is the Gemara's question.
(See also the NACHALAS DAVID cited in the following Insight for another approach.)
2) THE SOURCE FOR "TOSEFES SHEVI'IS"
QUESTION: The Gemara concludes that it is Rebbi Yishmael who maintains that the source for the law of Tosefes Shevi'is is a Halachah l'Moshe mi'Sinai. Rebbi Akiva, however, derives the law of Tosefes Shevi'is from a verse and not from a Halachah l'Moshe mi'Sinai. According to Rebbi Akiva, there is no such Halachah l'Moshe mi'Sinai.
Although Rebbi Akiva maintains that the Halachah l'Moshe mi'Sinai is not necessary to teach the law of Tosefes Shevi'is, he should agree that the Halachah l'Moshe mi'Sinai is necessary to teach the leniency of "Eser Neti'os" -- the requirement to refrain from working the land before the arrival of the Shevi'is year does not apply to a field of young plantlings, which may be plowed until Rosh Hashanah of Shevi'is. Does Rebbi Akiva maintain that there is no such law of Eser Neti'os? That is unlikely, for the Mishnah in Shevi'is (1:6) records this law and mentions no one who argues with it. Moreover, the Mishnah later in Shevi'is (1:8) records the opinion of Rebbi Akiva in a discussion about how to differentiate between a "Neti'ah," a young plantling, and an "Ilan," a mature tree. If Rebbi Akiva maintains that there is no leniency for Neti'os and that they are no different from mature trees with regard to Shevi'is, then why does he discuss the definition of a Neti'ah? (TUREI EVEN to Rosh Hashanah 9a)
(a) The RASHASH in Shevi'is (1:6) answers that Rebbi Akiva indeed argues with the Halachah l'Moshe mi'Sinai of Eser Neti'os. According to Rebbi Akiva, there is no allowance to plow a field of young trees up until Rosh Hashanah of Shevi'is. Why, then, does Rebbi Akiva in the Mishnah there (1:8) discuss the difference between a Neti'ah and an Ilan, if the same Halachah applies to both?
The Rashash points out that the RAMBAM in Shevi'is (Perush ha'Mishnayos) explains that Rebbi Akiva's description of the difference between a "Neti'ah" and an "Ilan" is relevant to a different Halachah. The Mishnah in the beginning of Shevi'is (1:1) states that a "Sedeh Ilan," a field of mature trees, may be plowed during the year before Shevi'is only up until Shavuos (according to Beis Hillel). The Mishnah (1:2) then defines a Sedeh Ilan as a field which contains "three trees per Beis Se'ah." If the field has less than three trees per Beis Se'ah, it is not a Sedeh Ilan and may be plowed only until Pesach and not until Shavuos. The Rambam explains that if the trees in the field are not mature trees but young plantlings (Neti'os), the field is not considered a Sedeh Ilan and it may be plowed only until Pesach and not Shavuos. Only a field which contains ten Neti'os is considered a Sedeh Ilan which may be plowed until Shavuos. This Halachah necessitates a description of the difference between a Neti'ah and an Ilan.
According to the Rambam's explanation, Neti'os effect a stringency in the laws of Shevi'is (they may be plowed only until Pesach of the year before Shevi'is) and not a leniency. REBBI AKIVA EIGER (in Shevi'is) asks how the Rambam knows that there is a stringency associated with Neti'os, when the Mishnah there mentions only a leniency of Neti'os (the allowance to plow a field of Eser Neti'os until Rosh Hashanah). Moreover, even if there is such a stringency related to Neti'os, why does the Rambam not mention the main difference between a Neti'ah and an Ilan -- that one may be lenient with Neti'os and plow them until Rosh Hashanah?
The Rashash answers that the Rambam's source that there must be another Halachah associated with the status of Neti'os is from the fact that Rebbi Akiva in the Mishnah there discusses the definition of a Neti'ah. Why would Rebbi Akiva -- who maintains that there is no Halachah l'Moshe mi'Sinai of Eser Neti'os -- discuss what a Neti'ah is if it has no relevance to any Halachah? It must be that there is some other Halachah for which the definition of a Neti'ah is relevant. The Halachah that a Sedeh Ilan may be plowed until Shavuos of the year before Shevi'is is mid'Rabanan; the Rabanan determined how much work is needed for which type and number of trees or plants. The Rabanan determined that a field with three mature trees needs to be worked until Shavuos, while a field with less than three mature trees needs to be worked only until Pesach. Rebbi Akiva certainly does not argue with this Halachah of the Rabanan, as it is entirely unrelated to the Halachah l'Moshe mi'Sinai. For this reason, the Rambam explains that when Rebbi Akiva discusses what a Neti'ah is, he refers to the stringency associated with Neti'os. (The CHAZON ISH in Shevi'is 17:12 offers a similar answer for the Turei Even's question.)
(b) The CHAZON ISH (Shevi'is 17:12), however, considers this approach untenable because there still is no Tana who explicitly argues with the Mishnah which states unequivocally that a field of Eser Neti'os may be plowed until Rosh Hashanah of Shevi'is.
The Chazon Ish suggests instead that perhaps Rebbi Akiva agrees that there is a law of Eser Neti'os, but that its source is not a Halachah l'Moshe mi'Sinai. Rebbi Akiva derives the obligation of Tosefes Shevi'is from the verse, "be'Charish uva'Katzir Tishbos" -- "You shall cease from all plowing and reaping" (Shemos 34:21). However, that verse does not specify how much time before Shevi'is one must refrain from working the land. It must be that the Torah empowered the Chachamim with the authority to determine how much time before Shevi'is one must refrain from working the land, and to determine what types of field are included in the law of Tosefes Shevi'is. The Chachamim determined that the Torah excludes a field of Eser Neti'os from the law of Tosefes Shevi'is, and it permits one to plow such a field up until Rosh Hashanah of Shevi'is.
(c) The NACHALAS DAVID suggests that Rebbi Akiva indeed accepts the Halachah l'Moshe mi'Sinai. When the Gemara says that Rebbi Yishmael derives the obligation of Tosefes Shevi'is from the Halachah l'Moshe mi'Sinai and Rebbi Akiva derives it from a verse, it does not mean that Rebbi Akiva derives it solely from the verse. Rather, it means that Rebbi Akiva maintains that it would have been derived from a verse if not for the Halachah l'Moshe mi'Sinai.
According to this explanation, why is a verse necessary to teach Tosefes Shevi'is if the law is taught by a Halachah l'Moshe mi'Sinai (as the Gemara itself asks)? The Nachalas David says that this is not a question because the Gemara in Rosh Hashanah (9a) says that even Rebbi Yishmael, who explicitly states that the law is derived from the Halachah l'Moshe mi'Sinai, also requires a verse to teach the prohibition of Tosefes Shevi'is! TOSFOS there (DH v'Rebbi Yishmael) explains why Rebbi Yishmael needs a verse if he learns the law from a Halachah l'Moshe mi'Sinai: If there would have been no verse but only a Halachah l'Moshe mi'Sinai, we would not have learned the obligation of Tosefes Shabbos and Tosefes Yom Tov from the obligation of Tosefes Shevi'is, because "we do not derive other laws from a law taught by a Halachah l'Moshe mi'Sinai."
Similarly, Rebbi Akiva needs a verse in addition to the Halachah l'Moshe mi'Sinai in order to teach that the law of Tosefes applies to Shabbos and Yom Tov, just as it applies to Shevi'is. (Tosfos explains why the Gemara here does not use this logic to answer its question on Rebbi Akiva, but the Nachalas David does not accept Tosfos' argument and asserts that the Gemara here indeed uses this logic to explain the opinion of Rebbi Akiva.)
3) THE PROHIBITION AGAINST WATERING A FIELD WITH RAINWATER ON CHOL HA'MO'ED
OPINIONS: The Mishnah (2a) states that one may not water a field with rainwater (collected in a pit) during Chol ha'Mo'ed. The Gemara records an argument about the reason for this prohibition. Rebbi Ila'a in the name of Rebbi Yochanan says that the prohibition is because of a Gezeirah: if one would be permitted to use rainwater to water his field, he might assume that he is also permitted to use water from a cistern (Mei Kilon) because both are sources of collected water. Only spring water (which is not collected water but water which flows from a natural source) may be used. Water from a cistern may not be used because drawing it with a bucket on a pole (Kilon) involves excessive exertion (Tircha).
Rav Ashi argues and says that the reason why rainwater may not be used to water a field on Chol ha'Mo'ed is because the pit of rainwater becomes like a cistern itself. When the rainwater is drawn from the pit, the water level drops. Eventually, excessive exertion (a bucket attached to a pole) will be necessary to lift the water from the pit, effectively placing the pit into the category of a cistern.
The Gemara comments that the argument between Rebbi Yochanan and Rav Ashi depends on the ruling of Rebbi Zeira. Rebbi Zeira ruled that one is permitted to water a field from rivers which receive their water from swamps.
In what way is the ruling of Rebbi Zeira related to the argument between Rebbi Yochanan and Rav Ashi?
(a) RASHI (Kesav Yad), the RITVA, and others explain that when Rebbi Yochanan says that watering a field with rainwater on Chol ha'Mo'ed is prohibited because of a Gezeirah lest one use water of a cistern, he expresses a more stringent view than Rav Ashi. Rebbi Yochanan maintains that even rainwater from a pit which will remain perpetually full (because it has a constant supply of rain) may not be used for watering a field on Chol ha'Mo'ed because of the Gezeirah. This view is not in agreement with the ruling of Rebbi Zeira, because the Gemara concludes that the reason why Rebbi Zeira permits the water of rivers which originate from swamps to be used to irrigate fields on Chol ha'Mo'ed is because the swamp has a constant supply of water and will not dry up. Since it will not dry up, it will never become like a cistern. According to Rebbi Yochanan, however, the fact that the swamp has a perpetual supply of water does not matter; he maintains that since the water is collected rainwater and does not come from an underground spring, watering with it is prohibited because of a Gezeirah lest one assume that he may use water of a cistern.
The NACHALAS DAVID points out that this is the intention of RASHI (DH Rebbi Ila'a) here as well. However, the words of Rashi are confusing; two comments of Rashi are printed out of order, earlier than they are supposed to appear. The comments of Rashi in DH Naharos and in DH Mutar belong after DH Rebbi Ila'a. Those two comments address Rebbi Yirmeyah's question to Rebbi Zeira in the next stage of the Sugya.
(b) RABEINU CHANANEL explains that at this point in the Sugya the Gemara assumes that Rebbi Zeira's statement about rivers that come from swamps refers to swamps that might run out of water, and yet he still permits watering fields from such rivers. This is counter to the opinion of Rav Ashi, who prohibits watering a field from a rainwater-pit lest it run out of water and become a cistern. Accordingly, Rav Ashi would also prohibit watering a field from a river whose source of water might dry up.
Rebbi Yochanan's opinion, however, conforms with Rebbi Zeira's ruling. Although Rebbi Yochanan maintains that the Rabanan enacted a Gezeirah to prohibit watering a field with rainwater, that Gezeirah does not apply to rivers which draw their water from swamps. The reason why Rebbi Yochanan does not apply the Gezeirah to such rivers is because he maintains that the Gezeirah is applicable only where one must take out the water with a bucket (such as from a pit of collected rainwater). Where one does not need to take out water with a bucket (such as from a river which brings the water directly to the field), the Gezeirah does not apply.
However, in the next stage of the Gemara (when Rebbi Zeira responds to Rebbi Yirmeyah's question), the Gemara concludes that Rebbi Zeira permits the water from swamps only if they do not dry up. According to this conclusion, even Rav Ashi agrees with Rebbi Zeira, since there is no fear that the swamp will dry up and become like a cistern (and thereby create a situation where excessive Tircha is necessary in order to get the water).