Bechoros 17b

בכורות י״ז ע״ב

Bekhorot 17b

Learn Bechoros 17b step by step: Aramaic beside English, every question, answer and proof colour-coded.

Open Bechoros 17b in Gemara Clarity

Topic

Twin firstborn animals, and whether people can measure with perfect precision (צמצום) according to the רבנן

Overview

This amud finishes the משנה about twin firstborn animals. It covers the priestly gifts from the doubtful twin, what happens if one twin dies, and the case of a male and a female twin. Then the גמרא asks a new question. רבי יוסי הגלילי holds that perfect precision (צמצום) is possible even in things Heaven controls. The רבנן hold it is impossible there. But what do the רבנן hold about things people do on purpose? The גמרא tries several proofs: the red line around the מזבח, the exact measurements of the vessels, a clay vessel broken into equal halves, and רבי אליעזר's ruling about a body found exactly between two towns. Each of the first three proofs is pushed away. The rejection of the last proof begins at the end of the amud and continues on the next amud.

Opening lines

The steps (13)

1. StatementThe doubtful twin still owes the priestly gifts
2. StatementIf one twin died: split it, or the owner keeps it
3. StatementA male and a female twin: the priest gets nothing
4. QuestionCan people measure exactly, according to the רבנן?
5. ProofProof from the red line around the מזבח
6. RejectionThe line was made a little wider
7. ProofProof from the exact sizes of the vessels and the מזבח
8. RejectionDoing your best is enough there
9. ProofProof from a clay vessel broken into equal halves
10. RejectionClay is different because its edges are jagged
11. ProofA body found exactly between two towns
12. ProofSuggested reason: people can measure exactly
13. RejectionThe rejection begins: No, רבי אליעזר...