מצידו בעשר מראשו בארבעה
if it was breached from its side, the side wall of the alleyway, carrying within the alleyway is prohibited if the breach is ten cubits wide. But if it was breached from its front, the wall that faces the public domain, carrying within the alleyway is prohibited even if the breach is only four handbreadths wide.
מאי שנא מצידו בעשר דאמר פתחא הוא מראשו נמי נימא פתחא הוא
The Gemara poses a question: What is the difference such that carrying is prohibited due to a breach from the side only if the breach is ten cubits? This is because you say that up to ten cubits it is deemed an entrance. If the breach is in the front, let us also say it is an entrance, and carrying should be permitted if the breach is less than ten cubits.
אמר רב הונא בריה דרב יהושע כגון שנפרץ בקרן זוית דפתחא בקרן זוית לא עבדי אינשי
Rav Huna, son of Rav Yehoshua, said: We are dealing with a case where the breach is in a corner. Since people do not make an entrance in a corner, a breach of this kind cannot be viewed as an entrance, and if the breach is larger than four handbreadths it must be sealed.
ורב הונא אמר אחד זה ואחד זה בארבעה וכן אמר ליה רב הונא לרב חנן בר רבא לא תפלוג עלאי דרב איקלע לדמחריא ועבד עובדא כוותי אמר ליה רב בקעה מצא וגדר בה גדר
Rav Huna disagreed with Rav Ḥanin bar Rava and said: There is no distinction between the side and the front, for in both this case and that, a breach of up to four handbreadths is allowed. And so Rav Huna said to Rav Ḥanan bar Rava: Do not dispute me, as Rav himself arrived at a place called Damḥarya and performed an action, i.e., issued a practical ruling, in accordance with my opinion. Rav Ḥanan bar Rava said in response to him: No proof can be brought from that incident, for in that case Rav found an unguarded valley and fenced it in, i.e., , Rav saw the need to add a safeguard and was therefore stringent in this case. His ruling, however, was not generally applied.
אמר רב נחמן בר יצחק כוותיה דרב הונא מסתברא דאיתמר מבוי עקום רב אמר תורתו כמפולש ושמואל אמר תורתו כסתום
Rav Naḥman bar Yitzḥak said: Rav Huna’s opinion stands to reason, as it was stated that the amora’im disagree about the following issue: With regard to a crooked, L-shaped alleyway that opens onto the public domain at both ends, Rav said: Its law is like that of an alleyway that is open on two opposite sides, and it must be treated in a manner suitable for such an alleyway, i.e., an opening in the form of a doorway must be constructed at both ends, or else such an opening must be constructed at the point where the two arms of the alleyway meet and a side post or a cross beam must be placed at each end. And Shmuel said: Its law is like that of an alleyway that is closed on one side, and all that is necessary is a side post or a cross beam at each end.
במאי עסקינן אילימא ביותר מעשר בהא לימא שמואל תורתו כסתום
The Gemara clarifies the particular circumstances of the case: With what are we dealing? If you say that the width of the alleyway at the point of the turn is more than ten cubits wide, in this case, would Shmuel say that its law is like that of an alleyway that is closed on one side? With an opening of that size, it must be considered like an alleyway that is open on both ends.
אלא לאו בעשר וקאמר רב תורתו כמפולש אלמא פירצת מבוי מצידו בארבעה
Rather, are we not dealing with a case where the width of the alleyway at the point of the turn is ten cubits or less, and Rav nonetheless said that the law of such an alleyway is like that of an alleyway that is open on both ends. Apparently, a breach in the side wall of an alleyway renders it prohibited to carry even if it is only four handbreadths wide, in accordance with the opinion of Rav Huna.
ורב חנן בר רבא שאני התם דקא בקעי בה רבים
And Rav Ḥanan bar Rava argues that the cases cannot be compared: It is different there, in the case of the L-shaped alleyway, for many people cross through the opening from one arm to the other. Since in practice the alleyway is open to regular traffic, the ruling is stringent even with regard to a small breach.
מכלל דרב הונא סבר אף על גב דלא בקעי בה רבים מאי שנא מדרבי אמי ורבי אסי
The Gemara asks: Can it be inferred from this that Rav Huna holds that even if many people do not cross through the opening, a breach of four handbreadths still prohibits carrying? What is the difference between this case and the case of the ruling of Rabbi Ami and Rabbi Asi cited earlier, that an upright board of four handbreadths suffices in order to allow a breach of up to ten cubits?
התם דאיכא גידודי הכא דליכא גידודי:
The Gemara answers: There, there are remnants of a wall that render it difficult to pass through the breach, and therefore that breach does not annul the partitions. However, here, there are no remnants of a wall.
תנו רבנן כיצד מערבין דרך רשות הרבים עושה צורת הפתח מכאן ולחי וקורה מכאן חנניה אומר בית שמאי אומרים עושה דלת מכאן ודלת מכאן וכשהוא יוצא ונכנס נועל בית הלל אומרים עושה דלת מכאן ולחי וקורה מכאן
The Sages taught in a baraita: How does one render a public thoroughfare fit for carrying by means of an eiruv? He constructs an opening in the form of a doorway from here, on one side of the thoroughfare, and a side post or a cross beam from here, on the other side. Ḥananya disagrees and says: This is the subject of an early dispute between tanna’im, for Beit Shammai say: He constructs a door from here, on one side, and a door from here, on the other side, and when he exits and enters, he must lock the door. It is not sufficient to construct a symbolic door; rather, there must be a door that actually closes. And Beit Hillel say: He constructs a door from here, on one side, and a side post or a cross beam from here, on the other side.
ורשות הרבים מי מיערבא והתניא יתר על כן אמר רבי יהודה
The Gemara raises a fundamental question: Can a public domain be rendered fit for carrying by means of an eiruv? Wasn’t it taught in a baraita: Furthermore, Rabbi Yehuda said: