Eruvin, Chapter 4, Mishnah 6. This mishnah continues the discussion of the previous one. There we saw the position of the Sages: a person who was traveling on the road and fell asleep, and Shabbos began while he was still sleeping, does not receive two thousand amos but only four amos in which to walk. Here the mishnah comes to discuss: what is the law regarding two people who were sleeping six amos apart from one another, and woke up after Shabbos had already begun? Since each one has only four amos, and there are six amos between them, their walking areas overlap by two amos.
Two People Whose Amos Partially Overlap:
"Hayu shenayim, miktzas amos shel zeh besoch amos shel zeh - mevi'in ve'ochlin be'emtza, uvilvad shelo yotzi zeh mitoch shelo lesoch shel chaveiro" - when part of one person's four amos extends into his fellow's four amos, and in our example there are two shared amos, both of them may bring their food and eat together in that area, joining one another in the two shared amos. The permission is conditional on a person not taking his objects, which are bound by the limit of his own four amos, into his fellow's area that does not overlap, since those objects may not move into that zone. Therefore:
The shared objects remain within the two amos that both of them share.
Each one may return his own objects to his own private two amos, but not to his fellow's private two amos.
If There Were Three:
"Hayu sheloshah, veha'emtza'i muvla beineihen - hu mutar imahen vehen mutarin imo, ushenayim hachitzonim asurim zeh im zeh" - the middle one overlaps with both of the others: two amos shared with the person to his right, and two amos shared with the person to his left. Therefore the middle one and the outer ones are permitted with each other in the overlapping areas, but the two outer ones are forbidden to share with each other, since they have no overlapping area at all and cannot reach one another.
Rabbi Shimon's Words - The Analogy of the Three Courtyards:
Rabbi Shimon seeks to rely on a case in which he disagreed with the Sages, and to draw a parallel between the two cases, in order to prove that the law in the other case follows his opinion.
"Amar Rabbi Shimon: lemah hadavar domeh? Lesholosh chatzeros hapesuchos zu lazu ufesuchos lireshus harabim" - three courtyards that open into one another, and each of them also opens into a public domain. Even though they open into one another, since each of them has an opening to the public domain they do not restrict one another, and they need not make an eruv with one another; each is independent of the other, since they all have access to the public domain. However, if they wish to, they may make an eruv together.
In the case before us, each of the two outer courtyards made an eruv with the middle courtyard, but not with each other. Says Rabbi Shimon: "Eirvu shetayim hachitzonos im ha'emtza'is - hi muteres imahen vehen mutaros imah, ushetayim hachitzonos asuros zu im zu" - it is permitted to carry objects between each of the outer courtyards and the middle courtyard, but the two outer ones are forbidden with each other, since they did not make an eruv together, and they cannot take their objects and bring them into each other's domain.
The Reasoning Behind Rabbi Shimon's Words:
Elsewhere in the tractate the Sages disagreed with Rabbi Shimon and ruled that the two outer courtyards are forbidden even with the middle one, and may not bring their objects into the middle courtyard. Their reason: a decree, out of concern that if they are permitted to bring objects into the middle courtyard, they will eventually come to take their objects and transfer them into the third, outer courtyard, with which they are forbidden.
From here comes Rabbi Shimon's argument: in the case of three people sitting within their four amos, we permit the outer ones to bring their objects into the middle one's four amos, and we have no concern at all - and even though the outer ones are forbidden to bring their objects into each other's areas, and they do not share that area in common, we nevertheless permit them to bring objects to the middle one. The same should apply to three courtyards: the outer ones are forbidden with each other, but they should be permitted to bring their objects into the middle courtyard with which they made an eruv, and no decree should be imposed - just as no decree is imposed in the case of three people sitting on the road.
The Sages' Rejection:
The Sages reject the comparison. In the case of the three people, they are all sitting together, and the middle one sees with his own eyes the objects brought into his area from the person on his right and from the person on his left, and they are able to prevent any mishap of transferring the outer ones' objects from one to the other, since everything is happening right before their eyes.
In a courtyard, by contrast, people come and go and set things down, and it is possible that objects brought from one outer courtyard will be placed in the middle courtyard, and from there be brought by mistake into the second outer courtyard - and that is a mishap. Not everything takes place before the owners' eyes, and the objects do not carry any mark identifying them as belonging to a particular courtyard, so the matter is liable to become confused and lead to a prohibition. This is unlike the case of the three people, where everything is done before their eyes and they know to be careful.
In summary: in this mishnah we learned the laws of those who sleep on the road and have only four amos: two people whose amos overlap - they bring their food and eat in the middle, provided that a person does not take his objects into his fellow's non-overlapping area; and with three - the middle one is permitted with the two outer ones and they with him, and the two outer ones are forbidden with each other. Rabbi Shimon derived from here the case of three courtyards where the outer ones made an eruv with the middle one, that no decree should be imposed to forbid them, and the Sages rejected the comparison, since in the case of the three people everything is done before their eyes and there is no concern for a mishap as there is in courtyards.