Mishneh Torah, Defilement by Leprosy 5-7

Sugya Map

• Issue: Defining the susceptibility of "healing" wounds (sh'chin and michveh) to tzara’at vs. their status as "ordinary skin."
• Nafka Mina: Whether a baheret on a healing scab triggers immediate tumah or requires specific isolation protocols.
• Primary Sources: Leviticus 13:18-28; Mishneh Torah, Defilement by Leprosy 5:5-7.

Text Snapshot

Rambam defines the transition: "If the boil or the burn began to heal... with a scab like the thickness of a garlic peel... they impart impurity because of two signs: white hair or an increase in the size of the blemish" (Mishneh Torah, Defilement by Leprosy 5:5).

• Leshon nuance: The "garlic peel" (k'klipat ha-shum) is the threshold of hechsher—the moment the raw, festering wound (mordin) transitions into a state capable of manifesting the clinical signs of tzara’at.

Readings

• Ramban (Leviticus 13:18): Notes that the Torah treats the "scarring of the boil" as a distinct legal category to prevent the combination of disparate blemish types. His chiddush is that the "healing" state is not mere recovery, but a heightened state of vulnerability where the skin is re-indexed as susceptible flesh.
• Radbaz (ad loc): Argues that the separation of sh’chin and michveh is a gezeirat ha-katuv (decree) to ensure that the inspection process remains granular. Even if they are physiologically similar, they act as distinct legal domains.

Friction

• Kushya: If the healing scab is essentially "ordinary skin," why does it not combine with other beharot?
• Terutz: Rambam posits that because these areas are fundamentally "scabs" and not "flesh" in the primary sense, they lack the structural continuity required for hitztarfut (combination). They are "fit" to contract tzara’at but "unfit" to be part of a single, unified blemish.

Intertext

• Leviticus 13:22: The source for the expansion (pashat) being restricted.
• Shulchan Aruch, Yoreh Deah 196: While discussing niddah stains, the logic of "interim purity" (being pure, then impure, then pure) mirrors Rambam’s analysis of skin cycles in Mishneh Torah, Defilement by Leprosy 5:14.

Psak/Practice

The meta-halachic heuristic here is "Categorical Integrity." Just as a healing burn cannot "spread" into healthy skin, legal categories in halacha are often strictly siloed to prevent the expansion of stringencies (or leniencies) where the Torah explicitly divided them.

Takeaway

Halachic status often hinges on the threshold of stability—the "garlic peel" scab transforms a non-susceptible wound into a legally active site.