Niddah 20a

נדה כ׳ ע״א

Learn Niddah 20a step by step: Aramaic beside English, every question, answer and proof colour-coded.

Open Niddah 20a in Gemara Clarity

Topic

Identifying and checking the five colors of impure blood: red, black, crocus, water of earth, and diluted wine

Overview

The גמרא finishes defending its definition of the red color (אדום) of impure blood. אמימר then shows his colleagues what that red looks like, and רב אשי admits that someone who cannot tell such shades apart should not rule on blood. Next, the משנה's 'black like חרת' is explained as the darkest part of dry ink, and several אמוראים give familiar samples of the black shade, such as wax, grapes, a סיואה garment, and the bath attendants' cloths. שמואל and רב יצחק בר אבודימי argue about whether black blood is checked on a white cloth or a red one. עולא, רבי אמי בר אבא, רמי בר אבא, and בר קפרא then give different views on whether shades darker or lighter than the משנה's measures are טמא or טהור. For the crocus color, the standard is moist saffron, the middle leaf of the middle layer, still in its clumps of earth, and this settles four seemingly conflicting ברייתות. Finally, the גמרא explains how to prepare the 'water of earth' sample. It ends a question about stirring by hand with תיקו and reports practical rulings on where and how the earth check may be done.

Opening lines

The steps (45)

1. ChallengeDo reddish stains prove that a lighter red is also impure?
2. ResolutionThose stains looked like the other blood colors
3. Statementאמימר shows what the red of the משנה looks like
4. Conclusionרב אשי: someone who can't tell the shades apart shouldn't rule on blood
5. StatementThe black 'like חרת' means ink
6. ProofA ברייתא supports that the black is ink
7. ChallengeWhy not just say 'ink'?
8. Resolutionחרת means the darkest part of the ink
9. QuestionIs the measuring ink wet or dry?
10. Responseרבי אמי used dry ink
11. Statementשמואל: wax, ink, and grape colors are impure
12. Statementרבי אלעזר: olive, tar, and raven colors are pure
13. Statementעולא: like a סיואה garment
14. Statementעולא points out the black garment in פומבדיתא
15. Statementרבי יוחנן: like the bath attendants' cloths from overseas
16. ChallengeAre those cloths really black? רבי ינאי's burial request
17. ResolutionSame cloth, different look: worn as a garment or spread on a table
18. StatementAll blood colors are checked on a white cloth
19. StatementBlack blood is checked on a red cloth
20. ResolutionThey do not argue: black on red, the rest on white
21. ChallengeThen שמואל should have said 'except for black'
22. ResolutionThey argue about black itself
23. StatementFor every color: darker is impure, lighter is pure, just like black
24. ChallengeWhy did the משנה mention only black?
25. ResolutionBlack needed its own mention because of רבי חנינא's idea
26. Statementרבי אמי בר אבא: darker or lighter, all are טמא except black
27. ChallengeThen what are the measures for?
28. ResolutionThe measures rule out a very faint shade
29. StatementAnother version: רמי בר אבא says darker or lighter, all are טהור except black
30. Statementבר קפרא: darker is טמא, lighter is טהור, except diluted wine
31. Proofבר קפרא is tested and rules טהור both ways
32. Conclusionרבי חנינא praises בר קפרא
33. StatementSaffron color means fresh, moist saffron
34. ChallengeFour teachings disagree about which part of the flower
35. Resolutionאביי: the flower has three layers of three leaves
36. ConclusionUse the middle leaf of the middle layer
37. Statementרבי אבהו: the crocus must still be in its clumps of earth
38. StatementWhich valley's earth is used for the 'water of earth' color
39. StatementHow to prepare the muddy water sample
40. QuestionWhat does 'not by hand but with a vessel' mean?
41. ProofA proof: the check is done only in a cup
42. RejectionThe proof fails: checking is not the same as stirring
43. ConclusionThe question is left unresolved
44. StatementThe earth check works only in its own place
45. StatementChecking with a dry clump of earth is condemned