We are studying Maseches Moed Katan, chapter 2, Mishnah 4, which deals with three matters that pertain to Chol HaMoed: purchasing property, moving objects from one house to another, and bringing utensils back from the craftsman's house.
"Ein lokchin batim, avadim u'behemah, ela l'tzorech hamoed o l'tzorech hamocher she'ein lo mah yochal" - one may not buy houses, slaves or animals unless it is for the needs of the festival or for the needs of the seller who has nothing to eat:
A person may not buy houses, slaves or animals on Chol HaMoed, unless the purchase is made for the needs of the festival. There is a second allowance as well: when the sale is needed for the seller, who has nothing to eat and must liquidate his assets in order to obtain cash. Without one of these reasons, these items may not be sold.
Why did the Mishnah single out these particular items - houses, slaves and animals, which are large, expensive purchases? Two understandings are offered:
The approach of Tosafos: The Mishnah means that specifically with these items, whose sale is public and which are large and costly, one might have thought that they are forbidden even when the purchase is for the needs of the festival. The Mishnah therefore teaches that since it is for the needs of the festival, it is permitted. But items that are not for the needs of the festival, and other items as well, are forbidden.
A second understanding: The Mishnah refers specifically to these items, because with other items, if a person needs them, he may buy them even when they are not for the needs of the festival, as long as it is a good deal and the like. These items, however, being so expensive, were permitted only when the purchase is for the needs of the festival.
"Ein mefanin mibayis l'vayis" - one may not move from house to house:
A person may not transfer objects - such as utensils or sacks of grain - from one house to another, because of the bother and difficulty involved in carrying them from place to place. The Mishnah continues: "Aval mefaneh hu l'chatzeiro" - but he may move things within his own courtyard. The Gemara explains that the allowance is to move from house to house within the same courtyard. It emerges that the Mishnah's prohibition of moving "from house to house" applies when the houses are not in the same courtyard.
"Ein meviin keilim mibeis ha'uman" - one may not bring utensils from the craftsman's house:
One may not bring utensils from the craftsman's house or from his shop on Chol HaMoed. Two understandings are offered for the reason:
Because of the bother: The prohibition stems from the exertion involved in transporting the utensils.
Because of suspicion: It looks suspicious, since onlookers will assume that he gave the utensil to the craftsman to be made on Chol HaMoed.
"V'im chosheish lahem - mefanan l'chatzer acheres" - and if he is concerned about them, he may move them to another courtyard:
If he is concerned about leaving the utensils in the craftsman's shop, lest they be stolen or because of some other problem, he may move them to another courtyard where they will be better protected, but he may not bring them into his own house. The Gemara explains that all this applies to utensils that are not needed for the festival, but utensils that are needed for the festival may be brought back, and there is no problem with that. Some explain that if he is concerned about them even in the other courtyard, he may bring them discreetly rather than publicly, and may even bring them into his own house.
In summary: In this Mishnah we learned three laws of Chol HaMoed. Buying houses, slaves and animals is permitted only for the needs of the festival or for the needs of a seller who has nothing to eat, and there is a difference of opinion as to why the Mishnah emphasizes these expensive items in particular. Moving objects from house to house is forbidden because of the bother, and is permitted only within the same courtyard. Bringing utensils from the craftsman's house is forbidden either because of the bother or because of suspicion, and one who is concerned for his utensils may move them to another courtyard, while for items needed for the festival, or where there is a genuine concern, he may even bring them home, discreetly.