Talmud - Eruvin 90a עירובין צ׳ א׳

that he built the upper story to protect the garden [tarbitza], not to access the roofs.

Rami bar Ḥama raised a dilemma: According to Rav, who holds that one may carry only within four cubits on each roof, if he carries an object two cubits on a roof and another two cubits on a pillar ten handbreadths high and four handbreadths wide adjacent to the roof, what is the halakha? Rabba said: With regard to what matter is he raising a dilemma? Is it with regard to a karmelit and a private domain that he is raising a dilemma? The roof is a karmelit and the pillar is a private domain; certainly carrying from one to the other is prohibited.

The Gemara explains that this was not in fact the dilemma, and Rami bar Ḥama, due to his keen mind, did not analyze the dilemma carefully and was imprecise in its formulation. Rather, this is the dilemma he is raising: If one carries an object two cubits on the roof of a house, and another two cubits on the slanted roof of a portico, a roofed structure without walls, before a house belonging to someone else, what is the halakha?

The Gemara elaborates on Rami bar Ḥama’s dilemma: Do we say that since neither this roof is fit for residence, nor is this portico roof fit for residence, it is regarded as one domain, and therefore carrying between them is permitted? Or perhaps since carrying from a roof to another roof is prohibited, carrying from a roof to a portico is likewise prohibited, as the latter is also a domain in and of itself.

Rav Beivai bar Abaye raised a similar dilemma: If one carries two cubits on the roof of a house and another two cubits on the roof of a ruin belonging to someone else, one side of which was completely open to a public domain, what is the halakha?

Rav Kahana said: Is that not precisely the same dilemma raised by Rami bar Ḥama with regard to a portico? Rav Beivai bar Abaye said: And did I come late [me’aḥer] merely to quarrel, and meddle in other people’s questions? That is not the case, as the two dilemmas are not identical. A portico is not fit for residence, while a ruin is fit for residence. Therefore, the halakha might differ in each case.

The Gemara is surprised by this explanation: And now that it is fit for residence, what dilemma is he raising? The situation is comparable to the case of two standard roofs. The Gemara answers: Rav Beivai was unaware of the resolution to the dilemma raised by Rami bar Ḥama, and therefore, he states the dilemma employing the style: If you say. If you say that a portico is not fit for residence, and therefore carrying is permitted, it can be argued that as a ruin is fit for residence, the legal status of its roof should be like that of a standard roof. Or perhaps that is not the case, as now in any event there are no residents in the ruin, and therefore its roof is not comparable to a standard roof. No resolution was found for these dilemmas, and they stand unresolved.

The Gemara discusses a different question. With regard to roofs that are level, i.e., with a height disparity of less than ten handbreadths, according to the opinion of Rabbi Meir, or an isolated roof that does not border other roofs, according to the opinion of the Rabbis, Rav said: It is permitted to move an object throughout the entire roof; and Shmuel said: One may move an object in it only within four cubits.

The Gemara seeks to clarify the conflicting opinions. Rav said that it is permitted to move objects throughout the entire roof. This is difficult, as there is an apparent contradiction between one statement of Rav and another statement of Rav. With regard to level roofs, Rav said that according to the Rabbis one may carry on each roof only within four cubits. The Gemara answers: There, in the case of a roof among roofs, the inner partitions between the houses are not conspicuous, and therefore, are not taken into consideration. Here, however, the outer partitions of a single house or group of houses are conspicuous, meaning that they are considered to extend upward and delineate the edge of the roof.

The Gemara returns to discuss Shmuel’s ruling. And Shmuel said: One may carry only within four cubits. Once again, it is difficult, as there is an apparent contradiction between one statement of Shmuel and another statement of Shmuel, who said that in the case of level roofs, according to the Rabbis one may carry throughout each separate roof. The Gemara answers: There, the area of the roof is no greater than two beit se’a; whereas here, the area is greater than two beit se’a. And these partitions of the house were erected for use below as partitions for the residence itself; they were not erected to serve as partitions for use on the roof above. Consequently, even if the walls are viewed as extending upward so that they constitute surrounding partitions for the roof, the legal status of the roof is like that of an enclosure greater than two beit se’a that was not enclosed from the outset for the purpose of residence; and the principle is that with regard to any enclosure greater than two beit se’a that was not enclosed from the outset for the purpose of residence, one may move an object in it only within four cubits.

It was further stated that these same amora’im disagreed with regard to a large ship. Rav said: It is permitted to move an object throughout the entire ship, as it is all one domain; and Shmuel said: One may move an object in it only within four cubits. The Gemara proceeds to clarify their respective opinions. Rav said: It is permitted to move an object throughout the boat,

Traduction : The William Davidson digital edition of the Koren Noé Talmud, with commentary by Rabbi Adin Even-Israel Steinsaltz.

Eruvin 90a explores carrying limits between rooftops, porticos, and ruined structures, weighing whether adjoining spaces count as one domain under Shabbat law.