ויקרא, פרק י״ג, פסוק ט״ו

The laws surrounding skin afflictions present a fascinating paradox. When a person's body is completely covered by the disease, they are surprisingly declared pure. However, the moment even a small patch of healthy skin reappears, their status immediately reverts to impure [ביאור שטיינזלץ].

This transition to impurity does not happen automatically. Unlike other physical impurities that take effect naturally, this condition depends entirely on the diagnosis and formal ruling of a priest. Even if the physical criteria for impurity are clearly present, the status change requires the priest to actively inspect the skin and formally declare the impurity [ביאור יש״ר, מלבי״ם, אילת השחר, ביאור שטיינזלץ].

The reappearance of healthy skin establishes a sweeping rule. Anytime an individual is purified because the affliction spread across their entire body, the return of any healthy skin immediately brings back their impurity. This holds true regardless of their previous stage in the purification process—whether they were just beginning, finishing weeks of quarantine, or already completely cleared [תורה תמימה, מלבי״ם]. This reversion occurs even if the healthy skin appears in unusual places, such as the tips of limbs, which normally do not contract impurity on their own [תורה תמימה, אדרת אליהו, רד צ הופמן]. The sudden presence of healthy tissue fundamentally changes the diagnosis, rendering the entire previous outbreak an impure affliction once again [רד צ הופמן].

The specific emphasis that the healthy skin itself is impure serves to exclude other scenarios. Primarily, it clarifies that only the return of healthy skin triggers this relapse into impurity, rather than the reappearance of a white hair or a bright spot [ביאור יש״ר, רש ר הירש, רד צ הופמן]. Furthermore, this rule applies specifically to someone whose full-body affliction had previously granted them a status of purity. It excludes a person who was completely covered in white from the very onset of the disease. Such an individual is considered impure from the beginning, and the sudden appearance of healthy skin on the tips of their limbs does not trigger this specific law of reverting to impurity [תורה תמימה, מלבי״ם, אדרת אליהו].

Finally, the text concludes by definitively identifying the condition as a skin affliction. The primary approach among commentators notes a grammatical nuance: the phrasing points directly back to the healthy skin itself, rather than the disease as an abstract concept [רש״י, מזרחי, חזקוני]. While earlier descriptions of impurity might have been misunderstood as referring to the person as a whole, this specific phrasing ensures the focus remains strictly on the skin [גור אריה]. Although the healthy skin is technically just a symptom indicating the disease rather than the affliction itself, the language is structured this way to fit the grammatical constraints of the text [ברכת אשר].