Eruvin 15a

עירובין ט״ו ע״א

Learn Eruvin 15a step by step: Aramaic beside English, every question, answer and proof colour-coded.

Open Eruvin 15a in Gemara Clarity

Topic

לחי העומד מאליו: the dispute of אביי and רבא, whether it extends to a מחיצה, and whether a לחי is a מחיצה or a היכר

Overview

The גמרא brings a dispute between אביי and רבא about a לחי העומד מאליו, a post at the entrance of a מבוי that was not put there to be a לחי. At first it says they argue only when people relied on the post from before שבת. אביי accepts it, and רבא rejects it because it was not made for this purpose. The גמרא then assumes they also argue about a מחיצה that was not made to be a wall. It tests this against a סוכה among trees, trees and reed hedges serving as a דיומד, and a low-hanging tree, and it deflects each proof by saying the items were made on purpose. A ברייתא about a natural mound and cavity cannot be deflected this way. So the גמרא reframes the dispute: everyone agrees natural walls count. אביי holds that a לחי works as a מחיצה, while רבא holds that it is a היכר, which must be made by hand. Two ברייתות about wall stones and a recessed wall are deflected, but a story about רב and a palm tree seems to support אביי. The balcony of בר חבו shows they argue even when people relied on the item. A new משנה then begins: a לחי may be made from anything, even a living creature, though רבי מאיר forbids it.

Opening lines

The steps (34)

1. StatementDispute over a side post that stands by itself
2. StatementNarrowing where the dispute applies
3. StatementThe reasons of אביי and רבא
4. StatementAssuming the dispute also applies to a partition
5. ProofProof from a סוכה built among trees
6. RejectionThe trees were planted for this purpose
7. ChallengeThen the משנה is obvious
8. ResolutionThe משנה teaches there is no גזירה
9. ProofProof from a tree, fence, or reeds serving as a double post
10. RejectionThe items were made for this purpose
11. ChallengeThen why state the obvious?
12. ResolutionIt teaches the rule about gaps between reeds
13. ProofProof from a tree whose branches hang low
14. RejectionThe tree was planted for this purpose
15. ChallengeThen why is carrying limited to two בית סאה?
16. ResolutionWhy the tree area is limited to a בית סאתים
17. ProofProof from a mound, a cavity, and standing grain
18. ChallengeThe deflection of made on purpose does not work here
19. ResolutionNew framing: everyone agrees on walls, the dispute is about a לחי
20. ConclusionWhy אביי and רבא disagree about a natural לחי
21. ProofProof from protruding wall stones
22. RejectionThe stones were built for this purpose
23. ChallengeThen the ruling is obvious
24. ResolutionPeople might think the stones were for joining a building
25. ProofProof from a wall with a recessed side
26. RejectionThe wall was also made for this purpose
27. ChallengeThen what is the lesson?
28. ResolutionA לחי seen only from outside still counts
29. ProofThe story of רב, the fallen side post, and the palm tree
30. ProofDrawing the inference from רב's answer
31. QuestionSuggesting that אביי and רבא agree when the item was relied on
32. RejectionThe balcony of בר חבו shows they disagree even when relied on
33. StatementNew משנה: a side post may be made from anything, even a living creature
34. StatementA living creature used as a grave covering spreads impurity