Gemara

(Beraisa #1): One may brew beer on Chol ha'Mo'ed for the sake of the festival, but not for after the festival. If one brewed and some was left over, it is permitted, as long as he does not scheme.

Contradiction (Beraisa #2): One may brew beer of dates or barley on Chol ha'Mo'ed for the sake of the festival, but not for after the festival. Even if one has old beer, he may scheme to (brew and) drink new beer.

Answer: Tana'im argue about whether or not one may scheme:

(Beraisa): One may not scheme;

R. Yosi bar Yehudah permits scheming.

Shabbos 139b - (Rabah bar Rav Huna): (Chachamim forbid hanging a strainer only because this is a weekday act.) One may scheme and hang it in order to put pomegranates in it, and put dregs in (to strain out their wine).

(Rav Ashi): He must actually put in pomegranates.

Question: Why is this different than the following?

(Beraisa): One may brew beer of dates or barley on Chol ha'Mo'ed for the sake of the festival, but not for after the festival. Even if one has old beer, he may brew and drink new beer.

Answer: There, it is not evident. Here, it is evident (a strainer is normally used for straining).

Rabanan (to Rav Ashi): Rav Huna bar Rav Chivan is a Chacham that schemes! He put a (clove of) garlic in a barrel of wine to seal the opening, and said that he did so to store away the garlic. Also, he went to sleep in a (Nochri's) ferry (knowing that the Nochri will cross the river) in order to guard his fruit on the other side, and said that he intended to sleep!

Rav Ashi: He schemes about mid'Rabanan laws. He is a Chacham, so he will not come to overtly transgress.

Rishonim

Rif and Rosh (2:16): One may brew beer on Chol ha'Mo'ed for the sake of the festival, but not for after the festival. If one brewed and some was left over, it is permitted.

The Rif (Shabbos 57b) brings the Gemara in Shabbos.

Ran (DH Ma'arim): He must put pomegranates in the strainer before putting dregs in.

Rambam (Hilchos Yom Tov 7:8): One may brew beer of dates or barley on Chol ha'Mo'ed for the sake of the festival, but not for after the festival. Even if one has old beer, he may scheme to (brew and) drink new beer.

Magid Mishnah: The Rambam is lenient because it is a mid'Rabanan matter. The Ritz Gei'us forbids scheming; the Rif did not discuss this.

Rebuttal (Ra'avad): This is like R. Yosi b'Rebbi Yehudah, but the Halachah follows Chachamim who argue with him. Surely, if the new beer is better than the old it is permitted without scheming.

Defense #1 (Magen Avraham OC 533:3): The Gemara answered that such a scheme is permitted because it is not evident, i.e. that he has other beer.

Defense #2 (Migdal Oz): The Rif did not mention scheming because he forbids, like the Ra'avad. The following bothered the Rambam. Beraisa #1 forbids scheming to intentionally make more than needed, and Beraisa #2 permits making new even though he has old. Why did the Gemara call this a contradiction? Also, Beraisa #2 says 'We do not scheme 'in this way'. This suggests that another scheme is permitted! Also, why does the Gemara say that Tana'im argue about this? It should merely say that Beraisa #2 is R. Yosi b'Rebbi Yehudah! Therefore, the Rambam explains that all permit to scheme to make and drink new beer. Tana'im argue about scheming to make more than needed. The Rambam rules like Chachamim and permits only scheming to make new.

Rosh (Shabbos 20:5): Rabah bar Rav Huna permits hanging a strainer to put pomegranates in it, and to put dregs in. Rav Huna requires him to actually put in pomegranates. Some schemes are permitted to everyone, such as salting one piece of meat at a time (and then deciding to eat a different piece - Beitzah 11b). Some are permitted only for a Chacham, such as putting garlic in a barrel to seal the opening. Some are forbidden to everyone and Chachamim were more stringent than about one who transgressed b'Mezid, e.g. one who did not make Eruv Tavshilin may not cook extra for Shabbos. Tana'im argue about some cases, e.g. if Oso v'Es Beno fell into a pit on Yom Tov, one may not bring both of them up since only one may be slaughtered today.

Poskim

Shulchan Aruch (OC 533:1): One may grind flour or brew beer from dates or barley only for the need of the Mo'ed. One need not skimp to make the minimum necessary. He may make liberally, and if there is leftover it is permitted. One may not scheme to make more than is necessary. If he has flour or beer, he may not say 'I want only from the new'. He may grind to make flour if he has bread, for fresh bread is better.

Beis Yosef (DH veha'Rambam): Only the Rambam permits scheming, so we do not follow him.

Mishnah Berurah (4): We permit even beer from barley even though it is a big exertion.

Mishnah Berurah (5): If someone else owns the mill and he is unwilling to grind a small amount, one may grind more, for he cannot grind less.

Mishnah Berurah (6): If one schemed, it is permitted to eat it. However, some say that we are more stringent about scheming than Mezid, and forbid.

Kaf ha'Chayim (9): Even on Yom Tov if one schemed it is permitted, for the Rambam permits scheming. Some say that it suffices to eat a k'Zayis of what he made.

Mishnah Berurah (9): Some Poskim permit scheming. We do not protest if someone relies on them. Some say that even these Poskim permit only if it is not evident that he schemes, e.g. when he has old and makes new. All forbid to grind or brew a large amount, for it is clearly for after Yom Tov.

Kaf ha'Chayim (13): If one will not be able to bake right after Yom Tov, he may intentionally make extra, since this scheme is not evident. In particular it is permitted if he makes only one loaf, for it is all one exertion.

Rema: Likewise, if the new beer is better than the old it is permitted without scheming.

Mishnah Berurah (10): Even if one has clean bread, he may bake fresh coarse bread for Chol ha'Mo'ed. It is forbidden to do so on Yom Tov.

Gemara

(Shmuel): If a Nochri was hired b'Kiboles (i.e. b'Kablanus, to finish a job for a fixed sum), it is forbidden for him to work (on Shabbos) inside the Techum (lest people think that the Yisrael hired him today). He may work outside the Techum (people do not go there).

(Rav Papa): Even outside the Techum is forbidden if there is a city (even of Nochrim) nearby (lest they think that the Yisrael hired him today).

(Rav Mesharshiya): Even outside the Techum, far from any city is permitted only on Shabbos and Yom Tov, for Yisraelim do not go there, but it is forbidden on Chol ha'Mo'ed, for people often go there.

Mar Zutra brei d'Rav Nachman hired Nochrim b'Kablanus to build a house outside the Techum. Rav Safra and Rav Huna bar Chinena refused to enter. Some say that even Mar Zutra did not enter.

Question: Shmuel permitted this!

Answer #1: An important person should be stringent.

Answer #2: Mar Zutra supplied them with straw on Shabbos.

Rav Chama permitted Avungarei (this will be explained) of the Reish Galusa to work on Chol ha'Mo'ed. Since they were not paid, they were merely fed, we are not concerned.

(Beraisa): One may hire Nochrim b'Kablanus on Chol ha'Mo'ed to work after the Mo'ed, but not during the Mo'ed.

The general rule is, one may tell a Nochri to do only what he himself may do.

(Beraisa): One may hire Nochrim b'Kablanus on Chol ha'Mo'ed to work after the Mo'ed, as long as he does not measure, weigh or count like on a weekday.

Rishonim

Rif and Rosh (2:6): We conclude that one may hire Nochrim b'Kablanus to do work only outside the Techum, only far from any city, and only to work on Shabbos and Yom Tov, but not on Chol ha'Mo'ed, for people often go there. (We do not discuss weekdays. There is no reason to forbid then!)

Rosh: The Ra'avad says that we do not discuss Kablanus of a field, for that is permitted even for an Avel, and all the more so on Chol ha'Mo'ed. We do not discuss Kablanus for something detached, for that is permitted even on Shabbos; we permit giving skins or garments to a Nochri tanner or launderer just before Shabbos (Shabbos 7b). Rather, we discuss Kablanus to build. Since he was hired before Yom Tov, the Nochri may build it during the Mo'ed, for this is his own preference. However, we forbid inside the Techum or on Chol ha'Mo'ed due to suspicion, for people do not know that it is Kablanus.

Rif and Rosh (2:10): One may hire Nochrim b'Kablanus on Chol ha'Mo'ed to work after the Mo'ed, but not during the Mo'ed. The general rule is, one may tell a Nochri to do only what he himself may do. One may hire b'Kablanus on Chol ha'Mo'ed to work after the Mo'ed, as long as he does not measure, weigh or count like on a weekday.

Nimukei Yosef (DH Mekablin): The same applies to a Sachir (someone paid by the day). Some say that if one stipulated that he not work during the Mo'ed, we are not concerned if he does, similar to stipulating with sailors about Shabbos (Shabbos 19a).

Hagahos Ashri: If a Yisrael gave Kablanus to a Nochri and the work becomes known, such as farming or tending animals, he may not let him work on Chol ha'Mo'ed, even outside the Techum. It is permitted on Shabbos and Yom Tov if it is 2000 Amos from where Yisraelim live, since Yisraelim are not frequent there. Presumably, something that is done covertly is permitted even on Chol ha'Mo'ed.

Rambam (Hilchos Yom Tov 7:24): On Chol ha'Mo'ed one may not tell a Nochri to do something that he himself may not do.

Rambam (25): One may hire a Sachir on Chol ha'Mo'ed to work after the Mo'ed, as long as he does not measure, weigh or count like on a weekday. If a Yisrael gave Kablanus to a Nochri, he may not let him work on Chol ha'Mo'ed, even outside the Techum. This is because everyone knows that it belongs to the Yisrael, and they will suspect that the Yisrael hired him to work during the Mo'ed. Not everyone knows the difference between a Sachir and a Kablan.

Magid Mishnah: The Rambam discusses Kablanus of land. Clearly, whatever is permitted on Shabbos inside the Techum is permitted during the Mo'ed. The Rambam did not need to explain this.

Rosh (2:7): Rashi brings a version in which Kablanus for an Avel is forbidden in the Techum, lest people think that he hired workers after becoming an Avel. An Avel may hire workers only for Devar ha'Eved. Kablanus is permitted outside the Techum on Shabbos and Yom Tov, for people do not go there, but not on Chol ha'Mo'ed, for then people go there. Really, it is forbidden on any weekday! Perhaps the Chidush is that even though most people do not leave their residence on Chol ha'Mo'ed, still it is forbidden.

Question (Ba'al ha'Ma'or): Why is it forbidden on Chol ha'Mo'ed? Aveilus does not apply then!

Answer (Ba'al ha'Ma'or): Rather, we must distinguish between Kablanus, which applies to farming, and Kiboles, which applies to Metaltelim or building. Regarding farming, everyone knows that the worker owns a share of the produce and he works for his own benefit. In Kiboles the worker has no share in the work he does, so it is forbidden wherever it becomes known. The same distinctions regarding Avel apply to Kiboles on Shabbos and Yom Tov and Chol ha'Mo'ed. The jobs Beis Hillel permit giving to a Nochri before Shabbos do not become known. We do not distinguish Chol ha'Mo'ed from Aveilus without a source.

The Rosh (8) brings the two reasons why Rav Safra and Rav Huna (and some say, even Mar Zutra) did not enter the house that Nochrim built on Shabbos.

Nimukei Yosef (DH Mekablei): Mar Zutra's house was not pure Kablanus, for the workers used his straw to make bricks. It was built on Yom Tov against his will.

Korban Nesan'el (40): According to the second opinion, an important person need not be more stringent than others. This is the source for the Shulchan Aruch's ruling (OC 244:3) that one may not enter a house built b'Isur.

Rosh (9): The Reish Galusa's workers were doing labors permitted on Chol ha'Mo'ed, such as fixing benches. Nevertheless, it was permitted only because they received only meals. Receiving wages is like a weekday act.

Nimukei Yosef (DH bi'Gmara): The Avungarei were Nochrim who supervised the Reish Galusa workers and prodded them to work. Sometimes they themselves would help. They were not paid extra for their work; it was to find favor in the Reish Galusa's eyes.

Rashi (DH Avungarei): The Avungarei were people who arranged the tables.

Poskim

Shulchan Aruch (OC 543:1): On Chol ha'Mo'ed one may not tell a Nochri to do anything that he himself may not do.

Kaf ha'Chayim (3): This includes Isurim that are not Melachah, such as buying for after the Mo'ed.

Magen Avraham (1): For the need of a Mitzvah for Chol ha'Mo'ed one may tell a Nochri to do Melachah, for some permit even on Shabbos.

Sha'ar ha'Tziyon (544:10): A Beis ha'Keneses may be built through Nochrim if it will be finished and used on Chol ha'Mo'ed.

Mishnah Berurah (2): Even if it will be more expensive to hire someone after the Mo'ed, this is not Devar ha'Eved, for he does not now have something that he may lose.

Kaf ha'Chayim (5): If a Nochri worked for a Yisrael on Chol ha'Mo'ed, what he made is permitted.

Shulchan Aruch (2): If a Nochri accepted before Yom Tov to build a house for a Yisrael b'Kablanus, one may not let him build it on Chol ha'Mo'ed, even outside the Techum. If one hired him before Yom Tov to work b'Kablanus with Metaltelim in the Nochri's house, it is permitted.

Beis Yosef (DH u'Mah she'Chosav v'Afilu): The Tur says that it is proper not to enter a house built b'Isur. He holds that the Halachah follows the latter version, that Mar Zutra helped. The Gemara did not forbid, it merely told about important people that did not enter. Therefore the Tur does not forbid, he only says that it is proper, i.e. Midas Chasidus, to be stringent.

Taz (1): The Tur did not need to say that one may not help build it on Shabbos. In the second version, the Gemara teaches that one should be stringent if it was built b'Isur. In the first version it was built b'Heter, nevertheless an important person should be stringent.

Magen Avraham (2): The Shulchan Aruch holds that Mar Zutra's house was built on Yom Tov. Therefore we have no source to be stringent about something built on Chol ha'Mo'ed.

Machatzis ha'Shekel: The Tur says that the house was built on Chol ha'Mo'ed. The Shulchan Aruch did not bring that one should be stringent if the house was built b'Isur. The Magen Avraham deduced that the Shulchan Aruch disagrees with the Tur, and holds that the house was built on Yom Tov.

Beis Yosef (DH u'Mah she'Chosav v'Hani): Hagahos Maimoniyos says that we permit only Kablanus for Metaltelim in the Nochri's house, but a Sachir is never permitted.

Mishnah Berurah (3): Even though it is Kablanus, and the Yisrael does not command the Nochri to work during the Mo'ed, rather, the Nochri himself wants to, it is forbidden lest people think that he is a Sachir. (The Bi'ur Halachah (244:1 DH O Liktzor) discusses whether or not we are lenient if Kablanus is the norm in the city.)

Shulchan Aruch (3): On Chol ha'Mo'ed one may give work to a Nochri to do b'Kablanus or for a daily wage to do it after the Mo'ed, as long as he does not measure, weigh or count like on a weekday.

Kaf ha'Chayim (12): The Eliyahu Rabah says that the Poskim discuss giving to a Nochri, for one may not give to a Yisrael due to suspicion. However, the Magen Avraham permits giving to a Yisrael, and the Rambam and Ritva agree.

Kaf ha'Chayim (13): The Eliyahu Rabah says that it suffices to give it to be done after the Mo'ed. The Mishnah Berurah rules like the Magen Avraham, who requires an explicit stipulation.

Mishnah Berurah (10): One may not count clothing when giving it to a Nochri, except for linen garments in pressed circumstances. The custom is not to give laundry to Nochrim on Chol ha'Mo'ed, because we do not trust them without counting it.

Rema: Even if the Nochri does it during the Mo'ed it is permitted, since he stipulated to do it after the Mo'ed.

Kaf ha'Chayim (544:9): A case occurred in which Nochrim were Kablanim to build a Beis ha'Keneses. It was stipulated that they will not work on Shabbos and Yom Tov, but not about Chol ha'Mo'ed. The workers refused to desist on Chol ha'Mo'ed without being paid extra. The Noda bi'Yehudah (2: OC 103) allowed letting them build. There is no concern for suspicion of the Rabim, only for Chilul Hash-m in the eyes of the Nochrim. This does not apply here, for they see that Yisrael do Sechorah and permitted Melachos of Chol ha'Mo'ed, which they know are Asur on Yom Tov. Therefore, they think that Chol ha'Mo'ed is totally permitted.