Eruvin 50a

עירובין נ׳ ע״א

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Topic

רבה's two reasons for רב's 'under the tree' ruling, and challenges to the rule 'כל שאינו בזה אחר זה אפילו בבת אחת אינו' from מעשר, animal tithe, and the loaves of a תודה

Overview

Earlier, רב ruled that a person who says 'my שביתה is under this tree' has accomplished nothing. רבה gives two versions of the reason. In the first version, the person never pinned down an exact spot. In the second version, there is a rule: anything that cannot be done one after another cannot be done all at once either. The two versions give different results when a person asks for 'four אמות out of the eight.' The first version says this fails, and the second says it works. The גמרא then tests רבה's rule against other cases. Separating too much מעשר works because מעשר can take effect on half of each grain. Two animals called 'tenth' together become holy because animal tithe can work one after another when there is a mistake. Finally, the גמרא raises the case of a תודה brought with eighty loaves. רבי זירא narrows the dispute between חזקיה and רבי יוחנן, and the גמרא explains that חזקיה treats the extra forty loaves as a backup, so רבה's rule still stands. רבי יוחנן's reasoning continues on the next amud.

Opening lines

The steps (15)

1. Statementרבה's first reason: the spot is not defined
2. Statementרבה's second reason: what cannot be done one after another cannot be done at once
3. QuestionWhat is the practical difference between the two versions?
4. ResponseThe test case: acquiring four אמות out of eight
5. ResponseUnder the first reason, this case still fails
6. ResponseUnder the second reason, 'four out of eight' works
7. StatementRestating רבה's principle on its own
8. Challengeאביי challenges רבה from separating too much מעשר
9. Resolutionמעשר is different because it works on halves
10. ChallengeChallenge from two animals that came out together as the tenth
11. ResolutionAnimal tithe can work one after another when there is a mistake
12. ProofProof from the משנה about mistaken counting
13. ChallengeThe eighty loaves of a thanks-offering
14. Resolutionרבי זירא: everyone agrees on the clear-cut cases
15. ResolutionThe dispute is only when the owner said nothing specific