אמאי נימא כיון דאי בעי אמטויי מצי ממטי ליה אף על גב דלא אמטייה כמאן דאמטייה דמי
Why must one actually bring the eiruv to the place where he wishes to establish his residence? Let us say: Since if he wished to bring the eiruv there he could bring it, even though he did not bring it, it is considered as though he did bring it there. This follows the same reasoning proposed by Rav Yirmeya in the case of the basket: Since one can tilt it. The fact that this reasoning is not employed here indicates that the potential to do something is insufficient; rather, the deed must actually be done.
אמר רבי זירא גזירה משום יום טוב שחל להיות אחר שבת
Rabbi Zeira said: The fact that one must bring his eiruv the day before to the spot that he wishes to establish as his place of residence, and the potential to bring it there does not suffice, is a decree due to a Festival that occurs after Shabbat. In that case, the eiruv is valid for the Festival only if it was brought there before Shabbat, for it cannot be carried there on Shabbat. Since one cannot actually bring the eiruv there, it cannot be said: It is considered as though he did bring it there because had he wished to bring the eiruv he could have. Consequently, the Sages decreed that in all cases, the eiruv is only valid if it was actually brought to the designated spot, lest one come to think that even on a Festival that occurs after Shabbat it need not be brought there.
איתיביה נתכוון לשבות ברשות הרבים והניח עירובו בכותל למטה מעשרה טפחים עירובו עירוב למעלה מעשרה טפחים אין עירובו עירוב נתכוון לשבות בראש השובך או בראש המגדל למעלה מעשרה טפחים עירובו עירוב למטה מעשרה טפחים אין עירובו עירוב
Rav bar Shabba raised another objection from a different baraita: With regard to one who intended to establish his Shabbat residence in the public domain and placed his eiruv in a wall that is more than four cubits away from that location; if he placed the eiruv below a height of ten handbreadths above the ground, his eiruv is a valid eiruv; but if he placed it above ten handbreadths, his eiruv is not a valid eiruv because he is in a public domain while his eiruv is in a private domain. If one intended to establish his Shabbat residence on top of a dovecote or on top of a large cupboard, if he placed the eiruv in the dovecote or cupboard above ten handbreadths from the ground, his eiruv is a valid eiruv because both he and his eiruv are in a private domain; but if he placed it below ten handbreadths, the area in which he placed his eiruv is considered a karmelit, and his eiruv is not a valid eiruv because he cannot transport his eiruv from there to his own domain on Shabbat.
ואמאי הכי נמי נימא הואיל ויכול לנטותו ולהביאו לתוך עשרה אמר רבי ירמיה הכא במגדל מסומר עסקינן
Why should this be so? Here too, let us say that his eiruv should be valid even if it was placed below ten handbreadths, since one can tilt the cupboard and bring it to within ten handbreadths from the ground, in which case he and his eiruv would be in the same domain. Rabbi Yirmeya said: Here, we are dealing with a cupboard that is nailed to the wall so that it cannot be tilted.
רבא אמר אפילו תימא במגדל שאינו מסומר והכא במגדל ארוך עסקינן דאי ממטי ליה פורתא אזיל חוץ לארבע אמות
Rava said: Even if you say that it is referring to a cupboard that is not nailed to the wall, here, we are dealing with a very tall cupboard, such that were one to tilt it a little in order to bring the top of the cupboard within ten handbreadths from the ground, the top of the cupboard would project beyond the four cubits that constitute one’s Shabbat residence.
היכי דמי אי דאיכא כוותא ומתנא לייתיה בכוותא ומתנא דלית ליה כוותא ומתנא:
The Gemara asks: What, exactly, are the circumstances? If it is referring to a case where the cupboard has a window, and one has a rope at hand, let him bring it by means of the window and rope. In other words, let him lower the rope through the cupboard’s window and bring the eiruv with it, and he will not have to move the entire cupboard. The Gemara answers: Here we are dealing with a case where it does not have a window, and he does not have a rope at hand.
נתנו בבור אפילו עמוק מאה אמה וכו׳: האי בור דקאי היכא אילימא דקאי ברשות היחיד
We learned in the mishna: If one placed the eiruv in a pit, even if it is a hundred cubits deep, his eiruv is a valid eiruv. The Gemara asks: This pit, where is it situated? If you say that it is situated in the private domain,