1) COMPARING THE LAWS OF CHOL HA'MO'ED TO THE LAWS OF SHEMITAH
QUESTIONS: The Mishnah states that both on Chol ha'Mo'ed and during the Shemitah year, one may water a Beis ha'Shalchin (an irrigated field which does not have its own natural water source) with water from a spring, but one may not water a Beis ha'Ba'al (a field naturally irrigated by rainwater or springwater). However, one may not water a Beis ha'Shalchin on Chol ha'Mo'ed with rainwater or with water from a cistern.
The Gemara explains that the reasoning which underlies the laws in the Mishnah is that on Chol ha'Mo'ed, Melachah is prohibited unless it is needed for a Davar ha'Aved (to prevent a loss), in which case the Rabanan permitted it. However, the Rabanan permitted doing a Melachah for the sake of a Davar ha'Aved only when the Melachah does not involve excessive toil (Tircha Yeseira).
This reasoning explains the laws in the Mishnah as they apply to Chol ha'Mo'ed: one is permitted to water a Beis ha'Shalchin on Chol ha'Mo'ed because without that Melachah the field might dry up completely, as it has no natural water source. One is prohibited to water a Beis ha'Ba'al because watering that type of field is not a Davar ha'Aved; a Beis ha'Ba'al will not dry up if one does not water it, as it has its own natural source of water.
This reasoning also explains why one is permitted to water a Beis ha'Shalchin only from a spring, but not from rainwater or from a cistern. Although watering a Beis ha'Shalchin is a Davar ha'Aved, watering it from a cistern involves strenuous work and thus is prohibited.
(a) However, this reasoning explains only the laws as they relate to Melachah on Chol ha'Mo'ed. It does not explain how these laws relate to Shevi'is. During Shevi'is, there is no reason to differentiate between a Melachah done for a Davar ha'Aved and one that is not done for a Davar ha'Aved. If watering a field is a Melachah which is forbidden during Shevi'is, it should be forbidden in both a Beis ha'Shalchin and a Beis ha'Ba'al. If, on the other hand, watering a field is not forbidden during Shevi'is, it should be permitted in both types of fields. Why in the Shemitah year is there a difference between watering a Beis ha'Shalchin and watering a Beis ha'Ba'al?
(b) The same question may be asked about the prohibition against doing a Melachah, even for a Davar ha'Aved, which involves excessive toil (Tircha Yeseira). If the Melachah of watering a field is permitted during Shevi'is, why should it be forbidden when it involves excessive toil? There is no prohibition against exerting oneself excessively during Shevi'is. Only certain forms of Melachah which involve working the ground are forbidden during Shevi'is; all other forms of Melachah are permitted, and a person may put forth as much exertion as he wants. Why should the concern of Tircha Yeseira prohibit one from watering from a cistern during Shevi'is?
ANSWERS:
(a) The Rishonim offer different answers for why there is a difference between watering a Beis ha'Shalchin and a Beis ha'Ba'al during Shevi'is, if watering the ground is permitted during Shevi'is.
RASHI (as cited by TOSFOS to 6b, DH Marbitzin, and the NIMUKEI YOSEF) says that one indeed is permitted to water both types of fields during Shevi'is. When the Mishnah says that one may water only a Beis ha'Shalchin and not a Beis ha'Ba'al, it refers only to Chol ha'Mo'ed but not to Shevi'is. As Rava says (end of 2b), one is permitted to water any type of field during Shevi'is because the Torah's prohibition against Avodas ha'Karka (working the land) on Shevi'is does not include Hashka'ah (watering the land). Only certain forms of Toldos of Melachos, but not all forms, are prohibited mid'Oraisa.
Although the Beraisa (3a) notes that other Toldos are prohibited mid'Rabanan, Rashi asserts that watering is not one of them. The Beraisa distinguishes between Toldos which are prohibited mid'Rabanan because they involve farming-type labor, and others which do not involve "labor." The NIMUKEI YOSEF explains that watering plants is not considered a "labor" because it is done constantly for the upkeep of the field. A "labor" is an act done only on occasion in order to bring about a desired effect. Since watering must be done regularly it is not considered a labor, a "Melachah Chashuvah" (rather, it is just a "daily chore"). This is evident from the Beraisa (3a) itself which provides a long list of the Toldos which are prohibited mid'Rabanan but does not include watering among them.
(According to Abaye, who says (2b) that the Mishnah which permits watering a field during Shevi'is refers only to Shevi'is d'Rabanan, obviously even Rashi would agree that this allowance applies only to watering a Beis ha'Shalchin during Shevi'is. Since the prohibition against working the land during Shevi'is is mid'Rabanan, the Rabanan permitted watering the ground only for a Davar ha'Aved.)
TOSFOS (6b), however, mentions another opinion which asserts that the Mishnah permits watering only a Beis ha'Shalchin during Shevi'is (apparently even according to Rava). Although watering fields is permitted mid'Oraisa during Shevi'is, the Rabanan prohibited it when there is no loss involved (like the other Toldos which are prohibited mid'Rabanan). This is also the view of the RITVA who says that watering a field which is not a Beis ha'Shalchin and is not a Davar ha'Aved is prohibited mid'Rabanan according to the Mishnah. This also seems to be the opinion of the RAMBAM.
(b) Why, though, should a Melachah which involves excessive Tircha be prohibited during Shevi'is? The NIMUKEI YOSEF and RASHI (as cited by the Ritva) write that indeed there is no prohibition of excessive Tircha on Shevi'is and it is obvious that the prohibition against watering a field from a cistern applies only to Chol ha'Mo'ed and not to Shevi'is. This is also clear from the words of the Yerushalmi.
However, the RITVA argues and says that the simple reading of the Mishnah implies that the Halachos apply equally to Chol ha'Mo'ed and to Shevi'is. It must be that although the Torah does not prohibit acts of excessive Tircha on Shevi'is, the Chachamim prohibited watering in a manner which involves Tircha. They equated Shevi'is with Chol ha'Mo'ed for matters that involve working the ground.
(How does the Ritva reconcile his explanation with the very next line in the Mishnah which records a clear distinction between Shevi'is and Chol ha'Mo'ed? The Chachamim rule that during Shevi'is one may dig a water channel ("Amah"), but on Chol ha'Mo'ed one may only fix a water channel and not make a new one, presumably because that act is an excessive Tircha. The Chachamim clearly maintain that a Melachah for a Davar ha'Aved which involves excessive Tircha is prohibited on Chol ha'Mo'ed but permitted on Shevi'is, contrary to what the Ritva says.
The answer is that it is evident from the Gemara later (4b) that the reason why a water channel may be dug during Shevi'is according to the Chachamim is because it does not involve working the soil in order to cultivate produce. One simply makes a canal through which water will eventually be able to flow; he does not water or plant the field at that moment. (Even Rebbi Elazar ben Azaryah, who prohibits digging a water channel during Shevi'is, prohibits it only mid'Rabanan because of the concern that it will be mistaken for an act of tilling the soil.) Since the act of digging a water channel does not involve working the soil to produce fruit, any amount of exertion is permitted. The Ritva prohibits an act of exertion on Shemitah only where the Rabanan were lenient and permitted working the earth to produce fruit, such as in a situation of Davar ha'Aved.)
2) THE OPINION OF REBBI ELIEZER BEN YAKOV: WATERING TREES ON CHOL HA'MO'ED
QUESTION: The Gemara attempts to identify the Tana of the Mishnah who permits Melachah on Chol ha'Mo'ed for a Davar ha'Aved (in order to prevent a loss) but not for a Harvachah (in order to ensure a profit), and who prohibits a Melachah, even for a Davar ha'Aved, when it involves excessive Tircha. Rav Huna proposes that the Tana of the Mishnah is Rebbi Eliezer ben Yakov. In the Mishnah later (6b), Rebbi Eliezer ben Yakov says that one is permitted to bring water from one tree to another on Chol ha'Mo'ed, as long as he does not water the entire field (a Beis ha'Ba'al). The fact that Rebbi Eliezer ben Yakov prohibits watering the entire field implies that he rules that a Melachah for the sake of Harvachah is prohibited, as the Mishnah here says.
The Gemara asks that although Rebbi Eliezer agrees with one point of the Mishnah (that Melachah is not permitted for the sake of Harvachah), there is no indication that he agrees with the second point -- that Melachah which involves excessive Tircha is not permitted even for a Davar ha'Aved. Perhaps Rebbi Eliezer argues with this point and maintains that even when there is excessive Tircha, the Melachah is permitted for the sake of a Davar ha'Aved.
Rebbi Eliezer ben Yakov's opinion is difficult to understand. If he agrees with the first point of the Mishnah, that Melachah is not permitted for the sake of Harvachah, then why does he permit watering the trees themselves? Watering the trees is also an act done to ensure that the trees grow well and is not a Davar ha'Aved.
ANSWERS:
(a) TOSFOS (DH Moshchin) and RASHI (6b, DH Moshchin) explain that pouring water around the trees is indeed necessary in order to prevent a loss. Just as one is permitted to water a Beis ha'Shalchin because it is a Davar ha'Aved, one is permitted to water trees (even though the rest of the field around these trees is a Beis ha'Ba'al).
(b) RASHI on the Rif (DH Mashkin Beis ha'Shalchin) writes the opposite: watering trees is not something done to prevent a loss, since the trees will not suffer if they are not watered during Chol ha'Mo'ed. They are not considered like a Beis ha'Shalchin and do not have the status of a Davar ha'Aved. Only a field of Tevu'ah (grain and other vegetation) can have the status of a Beis ha'Shalchin. Why, then, does Rebbi Eliezer ben Yakov permit one to water trees on Chol ha'Mo'ed?
Rashi on the Rif (2a of the pages of the Rif, in his commentary to the Mishnah later) explains that the reason why this Melachah is permitted is because it involves no Tircha whatsoever and is done for Harvachah, to ensure a profit. The RITVA explains that there is no Tircha because there are grooves, like small trenches, in the field which lead from one tree to the next, and therefore bringing water from one tree to the other involves no effort. According to Rashi's approach, Rebbi Eliezer ben Yakov's wording is very precise: he says "Moshchin (we may draw, or let flow) water from one tree to the other" and he does not use the typical word "Mashkin" (we may irrigate). The word "Moshchin" implies that one is permitted only to draw water from one tree to another by letting the water flow from one tree to another through the grooves in the ground, because no Tircha is involved in this act.
In summary, according to Rashi on the Rif there are three levels of Melachah on Chol ha'Mo'ed:
1. A Melachah which involves no Tircha. This form of Melachah is permitted even for Harvachah (to ensure a profit) and not only for a Davar ha'Aved (to prevent a loss).
2. A Melachah which involves a slight Tircha. This form of Melachah is permitted only for a Davar ha'Aved, but not for Harvachah.
3. A Melachah which involves excessive Tircha, which is prohibited even for a Davar ha'Aved.

2b----------------------------------------2b

3) "HA'MEKAYEM B'KIL'AYIM"
OPINIONS: The Gemara quotes a Beraisa in which the Tana Kama and Rebbi Akiva argue with regard to one who transgresses the prohibition of Kil'ayim. The Tana Kama maintains that one who weeds out unwanted plants in order to help the forbidden plants of Kil'ayim grow, or one who covers the seeds of Kil'ayim with dirt to help them grow, is punished with Malkus. Rebbi Akiva maintains that even one who merely is "Mekayem" Kil'ayim is punished with Malkus.
To what act does Rebbi Akiva refer when he says "Mekayem b'Kil'ayim"?
(a) The ARUCH (cited by Tosfos to Avodah Zarah 64a, DH Rebbi Akiva) explains that when one merely allows Kil'ayim to grow in his field, he is punished with Malkus even though he did not plant the seeds. The Aruch explains that although there is a general principle that one does not receive Malkus for a "Lav she'Ein Bo Ma'aseh" (a prohibition transgressed passively, without an action), Rebbi Akiva does not agree with this principle and maintains that one does receive Malkus for a passive transgression. This is also the explanation of the RIVAN (Makos 21b, DH Mi Mishkachas).
(b) RASHI in Avodah Zarah (64a, DH Afilu) explains that "Mekayem" refers to one who builds a fence of thorns around the Kil'ayim in order to protect them. This is also the view of TOSFOS there (DH Rebbi Akiva). Tosfos points out that Rebbi Akiva agrees with the general principle that one does not receive Malkus for a "Lav she'Ein Bo Ma'aseh." In the case of "Mekayem," the person transgresses the prohibition actively (by building the fence). This is also the opinion of the RITVA, TOSFOS HA'ROSH, and the ME'IRI.
(c) RASHI here (DH Af ha'Mekayem), however, writes that "Mekayem" refers to one who notices Kil'ayim growing in his field and allows it to remain there (as the Aruch explains).
Why does Rashi here explain "Mekayem" differently from the way he explains it in Avodah Zarah?
1. The BEIS HA'LEVI (1:35:2) answers that Rashi maintains that "Mekayem b'Kil'ayim" means that one allows Kil'ayim to grow in his field, as the Aruch explains. However, one transgresses the prohibition of letting Kil'ayim exist only when he is the owner of the field (as is the case here in Moed Katan). The Gemara in Avodah Zarah, in contrast, refers to one who is "Mekayem" the Kil'ayim of a Nochri. In that case, "Mekayem" cannot mean that one merely lets it exist, because he has no obligation to destroy the Kil'ayim of a Nochri. Therefore, Rashi explains that "Mekayem" in that case refers to doing an act (building a fence) which demonstrates that he wants the Kil'ayim to exist.
2. The Beis ha'Levi suggests another answer. When a person performs an act which constitutes the beginning of a transgression, he may be punished for subsequent transgressions (which result from the initial act) even if he transgresses them passively. For example, one who wears a garment of Kil'ayim (Sha'atnez) is punished with Malkus if he does not remove the prohibited garment after he is warned, even though his failure to remove the garment is a passive transgression of the prohibition. Since he initially performed an act (donning the garment) which led to the transgression of the prohibition (of not removing the garment), he is considered to have transgressed the present prohibition with an action.
Rashi here understands that when the Gemara discusses a person who is "Mekayem b'Kil'ayim," it refers to the same person who planted the seeds in the first place. Since he initially performed an action when he planted the seeds, his present, passive transgression of allowing the Kil'ayim to remain is considered an action.
In contrast, the Gemara in Avodah Zarah refers to a case in which the seeds of Kil'ayim were planted by a Nochri. The Jew who subsequently allows those plants to remain did no action. Therefore, Rashi there explains that the Jew receives Malkus only if he did an action of building a fence to protect the Kil'ayim. This is also the explanation of the KORBAN ELITZUR (to Avodah Zarah) and the MEGILAS SEFER (Lavin #279). (See Insights to Makos 21:3.)
(d) TOSFOS in Bava Kama (81a, DH Ein) writes that when Rebbi Akiva says that one is punished with Malkus for "Mekayem b'Kil'ayim," he does not mean that the perpetrator actually receives Malkus. His transgression is a "Lav she'Ein Bo Ma'aseh" for which Malkus is not administered. Rather, Rebbi Akiva means that his act is a Torah prohibition, an Isur d'Oraisa.
The RI KURKAS (Kil'ayim 1:3) and the KORBAN ELITZUR (to Avodah Zarah) explain that Tosfos means that one receives Malkus d'Rabanan, according to Rebbi Akiva. (See YAD DAVID to Makos 21b for an alternative explanation of the words of Tosfos.)
(e) The KESEF MISHNEH (Kil'ayim 1:3) gives another explanation. After the Gemara here questions the Beraisa, it suggests that the Beraisa is expressing not two opinions, but only one opinion -- that of Rebbi Akiva. The Beraisa means that one who weeds out unwanted plants in order to help the forbidden plants of Kil'ayim grow, or one who covers the seeds of Kil'ayim with dirt to help them grow, is punished with Malkus because he has transgressed the prohibition of "Mekayem b'Kil'ayim" for which Rebbi Akiva maintains that one is liable. Rebbi Akiva is saying that only when one performs an action with the seeds themselves does he transgress the prohibition of "Mekayem b'Kil'ayim." In contrast, one who builds a fence around Kil'ayim is not punished with Malkus because his act is not performed with the seeds themselves.
A similar explanation is proposed by RABEINU CHANANEL here who writes that "Mekayem" refers to one who works the land and causes the plants of Kil'ayim to grow better. (Y. Montrose) (See also Insights to Avodah Zarah 64:1.)

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