Eruvin 12b

עירובין י״ב ע״ב

Learn Eruvin 12b step by step: Aramaic beside English, every question, answer and proof colour-coded.

Open Eruvin 12b in Gemara Clarity

Topic

Is a לחי or a קורה a real wall for throwing into a מבוי, and how do we tell a מבוי from a חצר?

Overview

The amud opens by finishing an earlier discussion: a ברייתא is limited to a case where remnants of the wall (גידודי) remain. רב יהודה then rules that throwing into an unmerged מבוי makes one liable if it has a לחי, but exempt if it has a קורה. רב ששת objects that food (a שיתוף) cannot change a domain, and a ברייתא says the עירוב makes no difference. So the גמרא rewords רב יהודה's ruling: it is about an alley open on both ends. This shows that רב יהודה, like רבה, holds a לחי is a wall and a קורה is only a sign. רבא holds both are only signs, and he answers two challenges from ברייתות. The גמרא then turns to shape: רב rules that an alley as long as it is wide is a חצר, which needs a פס of four טפחים, and רבי יוחנן confirms that courtyard boards must be four טפחים wide. רב נחמן's tradition, as the גמרא explains it, makes any space longer than it is wide, even by a tiny amount, a מבוי. The amud ends by returning to the משנה's disciple who spoke in the name of רבי ישמעאל.

Opening lines

The steps (22)

1. ResolutionThe case is where wall remnants remain
2. Statementרב יהודה: a side post makes it liable, a cross beam exempts
3. Challengeרב ששת: shared food cannot change the type of domain
4. ChallengeA ברייתא: liable whether or not they made an עירוב
5. ResolutionA corrected version of רב יהודה's ruling
6. ConclusionInference: a side post is a wall, a crossbeam is a sign
7. Statementרבא: both are only signs
8. ChallengeChallenge to רבא from a ברייתא about the side post
9. Resolutionרבא rereads the ברייתא: three walls versus two
10. ChallengeA challenge to רבא from רבי יהודה's two-houses case
11. Resolutionרבי יהודה holds that two walls are enough by Torah law
12. StatementA square alley cannot be fixed with a minimal side post
13. StatementA square alley cannot be fixed with a one-טפח beam
14. StatementA square alley is really a courtyard
15. ChallengeWhy not treat the side post as a narrow board?
16. ResolutionCourtyard boards must be four handbreadths
17. StatementDefining an alley and a courtyard
18. ChallengeDoes only a square shape count as a courtyard?
19. ResolutionSquare means not longer than wide
20. QuestionHow much longer must a מבוי be? שמואל's first view
21. ResponseEven slightly longer is enough
22. StatementReturning to the משנה: the disciple who spoke for רבי ישמעאל