Siman - Eruvin Daf 93
- לא מצינו מחיצה לאיסור
On Daf 92b Abaye said that we never find a case where adding mechitzos creates an issur that did not exist when the mechitzah was not there. The Gemara already challenged Abaye’s premise twice on Daf 92b and continues to challenge him on this Daf. Rabbah bar Rav Chanan said to Abaye, ולא מצינו מחיצה לאיסור – Do we not find examples of a mechitzah that causes an issur? But it was taught in a Baraisa regarding Kilayim, בית שחציו מקורה וחציו אינו מקורה – In a house that is half roofed and half unroofed, גפנים כאן מותר לזרוע כאן – if there are vines growing here (i.e. under the roofed part), it is permitted to plant grain or greens here (i.e. under the unroofed part), even without leaving the normally required distance of four amos between the vineyard and the plantings. Rashi explains that we apply the principle of פי תקרה יורד וסותם - the edge of the roof extends downwards and seals, partitioning the vineyard from the plantings.
Rabba bar Rav Chanan concludes his question, that if they had extended the roof so that it covers the entire house, it would be prohibited to plant grain or greens within four amos of the vines. We see from this that adding a roof, which is a form of mechitzah, can cause an issur. Abaye responded, התם סילוק מחיצות הוא – In this case, one is removing the partition. Meaning, the addition of the second half of the roof is not considered adding a mechitzah, but rather eliminating the mechitzah that had previously covered until the middle of the house and separated the vines from the plantings.
- A five amos high chatzeir with a five amos high wall
Rav Chisda says that גידוד חמשה ומחיצה חמשה – a chatzeir that is five amos higher than a neighboring chatzeir, and also has a wall that is five amos high, is not considered to have a ten amos wall. The Gemara questions this from a Baraisa which states that in the above case, the two adjoining chatzeiros may not have one eruv for both of them. We see from this that the גידוד חמשה ומחיצה חמשה do indeed combine to create a ten amos wall, thereby not allowing the two chatzeiros to join in one eruv. The Gemara answers that when Rav Chisda said that we do not look at this case as there being a ten amos wall, he meant this only in regards to the top chatzeir, being that one in the top chatzeir only sees the five amos of wall, however, in regards to the bottom chatzeir, from which ten amos of ground and wall can be seen, it is indeed considered a wall. Therefore, the Baraisa states that the two chatzeiros may not have one single eruv.
- A wall in between chatzeiros that falls on Shabbos
Rav Hoshaya asks what the law is about דיורין הבאין בשבת – residents arriving on Shabbos. Rashi explains that the case is that there is a wall in between two chatzeiros which fell on Shabbos. Each chatzeir had its own eruv, but now that the wall fell the two chatzeiros are one large chatzeir containing the residents of both. Rav Hoshaya’s question is if the residents of both chatzeiros are now forbidden to carry being that people who had not joined in their eruv (meaning the residents of the other chatzeir) have now joined them on Shabbos. The Gemara suggests a proof but then refutes it.
