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Eruvin 10b

עירובין י׳ ע״ב

Learn Eruvin 10b step by step: Aramaic beside English, every question, answer and proof colour-coded.

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Topic

Narrowing a wide מבוי, the rules of עומד and פרוץ (including the רב דימי–רבין dispute), and צורת הפתח

Overview

The גמרא explains how to narrow a מבוי whose entrance is wider than ten אמות. One way is to stand a board lengthwise down the alley. Another way follows רב יהודה: put a three-אמה board two אמות from the wall, which leaves an opening of exactly ten. The גמרא asks why other board arrangements were not suggested and tries to learn rules about עומד מרובה על הפרוץ and עומד כפרוץ. Each proof is rejected: a small board with open air on both sides is cancelled, and some setups are simply more work than the רבנן required. Next the גמרא worries that people will use the small gap instead of the main entrance. רב אדא בר מתנה answers that people do not leave a big entrance for a small one unless it saves them walking. The גמרא then brings a טומאה source about a leather seat and its hole, reported differently by רב דימי and רבין. אביי and רב דימי debate whether they truly disagree, and the dispute is narrowed to פרוץ כעומד. Finally the גמרא returns to the משנה: a צורת הפתח fixes a too-wide entrance, and the discussion of width and height continues on the next amud.

Opening lines

עוֹשֶׂה פַּס גָּבוֹהַּ עֲשָׂרָה

One makes a board ten handbreadths high

בְּמֶשֶׁךְ אַרְבַּע אַמּוֹת,

with a length of four cubits,

וּמַעֲמִידוֹ לְאׇרְכּוֹ שֶׁל מָבוֹי.

and stands it along the length of the alleyway.

אִי נָמֵי כִּדְרַב יְהוּדָה,

Alternatively, like Rav Yehuda,

The steps (26)

  1. StatementFirst method: a board set lengthwise down the alley
  2. StatementSecond method: רב יהודה's three-cubit board
  3. ProofWhy not two smaller boards? An inference about standing versus open sections
  4. RejectionRejection: here the air on both sides cancels the far board
  5. ProofThree one-אמה boards, and a proof that equal standing and open is forbidden
  6. RejectionThe surrounding open air cancels the boards
  7. ChallengeWhy not two boards of one and a half אמות
  8. ResolutionIt would work, but the רבנן did not demand that much effort
  9. ChallengeWorry that people will use the small opening instead of the big one
  10. ResolutionPeople do not leave a big entrance to use a small one
  11. ChallengeWhy is this different from רבי אמי and רבי אסי?
  12. ResolutionA shortcut makes the difference
  13. StatementA stool's leather and its hole combine to make a טפח
  14. QuestionWhat is the leather of a stool?
  15. ResponseIt is the leather cover of a toilet seat
  16. QuestionHow big can the hole be?
  17. Responseרב דימי's measurement: two, two, and two
  18. Responseרבין's measurement: one and a half, one and a half, and one
  19. Questionאביי asks: do you two really disagree?
  20. Responseרב דימי: no argument, just different finger sizes
  21. Rejectionאביי: you do disagree about adding up two sides
  22. Proofאביי proves the two reports are not the same
  23. Rejectionרב דימי pushes back that a big dispute doesn't fit either
  24. ConclusionThe real dispute: a gap exactly equal to the standing part
  25. StatementBack to the משנה: a doorway frame fixes a wide entrance
  26. StatementDoorway frame helps width, cornice helps height