Niddah, Chapter 2, Mishnah 7. The earlier mishnayos of this chapter dealt with where blood is found and what its location tells us about its origin. This mishnah turns to a different question entirely: the color of what is found. Not every fluid that emerges from a woman's body is dam niddah. Certain shades are classified as blood and render tamei; other shades are treated as a discharge of another kind altogether, and are tahor. The mishnah lists which is which.
The opening words state the count: "chamisha damim temei'im be'isha". Five distinct shades that appear in a woman carry tumah. Each of them belongs to the family of red, and they are distinguished from one another only by their depth and their tint.
- "Ha'adom", red itself, the plain shade of blood.
- "Vehashachor", black. This is understood as red blood that has congealed and darkened until it has turned black. It is tamei because it began as red.
- "Ukekeren karkom", like the corner of the crocus plant, a shade that likewise carries a reddish hue.
- "Ukemeimei adamah", like water that stands over earth, which takes on a brownish red tint.
- "Vehamazug", like diluted wine, whose color runs toward a purplish red.
Beis Shammai hold that the list is longer by two. To the five they add, in their words, "af kemeimei silton": the silton is a plant, and water in which it has been soaked takes on a reddish color all its own, unlike any of the five shades already named. Beis Shammai count that as a sixth tamei color. Their seventh is the liquid that comes off roasted meat, "uchemeimei basar tzali", whose color too is a brownish red. Beis Hillel disagree with both additions, "uveis Hillel metaharin": blood of those two shades is tahor in their view.
The mishnah then raises yellow: "hayeirok, Akavya ben Mahalalel metamei, vachachomim metaharin". Akavya ben Mahalalel ruled that a yellow discharge is tamei, while the chachomim ruled it tahor, holding that yellow is not blood at all but a secretion of another sort.
Rebbi Meir stakes out a position between the two. He grants the first half, "im einam metameim mishum kesem": a color of this sort is not among those that convey tumah by way of a stain. Nevertheless, he continues, it is "metameim mishum mashkeh", it retains the status of a liquid that is tamei. The practical difference is where it is found: yellow discovered on a garment as a stain does not render tamei, while yellow seen coming from the body itself does.
Then comes "Rebbi Yosi omer", and his ruling denies both sides of that distinction: "lo kach velo kach". Yellow conveys no tumah when it turns up as a stain on cloth, and it conveys none as a discharge from the body either. This is the opinion that the halachah adopts.