Gemara Clarity

Niddah 18a

נדה י״ח ע״א

Learn Niddah 18a step by step: Aramaic beside English, every question, answer and proof colour-coded.

Open Niddah 18a in Gemara Clarity

Topic

Blood in the פרוזדור (inside or outside the לול, floor or roof), and רבי יוחנן's list of three cases where חכמים treated a רוב as certain.

Overview

The amud opens by noting that אביי's version that follows the חזקה disagrees with רב קטינא. רבי חייא says blood found in the פרוזדור is definitely impure, while רב קטינא says it is impure only out of doubt. According to רב הונא they don't argue: one is talking about blood inside the לול, the other about blood outside it. רמי בר שמואל and רב יצחק בריה דרב יהודה say blood outside the לול is pure, so for them both rulings must be about the inner area. The גמרא answers that רבי חייא means blood on the floor of the פרוזדור and רב קטינא means blood on its roof. Then רבי יוחנן teaches that in three cases, מקור, שליא and חתיכה, חכמים followed the רוב and treated it as certain. The גמרא challenges his list with the nine stores and the nine frogs, and answers by narrowing the list first to טומאה and then to a woman's טומאה. At the end, it starts a new challenge from רבי יהושע בן לוי about a woman who crossed a river, which continues on the next amud.

Opening lines

וּפְלִיגָא דְּרַב קַטִּינָא.

And it disagrees with Rav Ketina.

לְרַב הוּנָא, לָא פְּלִיגִי —

According to Rav Huna, they do not disagree:

כָּאן מִן הַלּוּל וְלִפְנִים,

here, from the lul inward,

כָּאן מִן הַלּוּל וְלַחוּץ.

there, from the lul outward.

The steps (14)

  1. Statementאביי's חזקה version clashes with רב קטינא
  2. ResolutionAccording to רב הונא, they are talking about different spots
  3. QuestionWhat about רמי בר שמואל and רב יצחק?
  4. ResponseBoth must be about blood inside the לול
  5. ChallengeDo they then argue with רבי חייא?
  6. ResolutionFloor of the corridor versus roof of the corridor
  7. StatementThree places where חכמים treated a רוב as a certainty
  8. ProofThe afterbirth case: no afterbirth without a baby
  9. ProofThe shaped limb case: we assume a normal baby
  10. ChallengeIsn't the case of nine stores missing from the list?
  11. ResolutionThe list covers only impurity, not prohibitions
  12. ChallengeThe nine frogs and one creeping animal
  13. ResolutionThe list covers only a woman's impurity
  14. ChallengeA new challenge: the woman who crossed a river