<p><br /></p><p><br /></p><p>This episode presents Rav Akiva Eiger’s classic kasha on Tzaras Tzarah: why does the Torah require a special pasuk of “litzror” to asser the second co-wife? Once the first tzarah becomes Eishes Ach, she would seem to carry the full status of an ervah, and an ervah ordinarily extends its halachic effect to a co-wife automatically. What, then, necessitates a new pasuk?</p><p><br /></p><p>Rav Nachum’s yesod provides the framework: the halachos of yibbum operate within two distinct categories—issur and ptur mitzvah. An ervah does not merely forbid; she removes the mitzvah of yibbum and thereby creates a ptur that applies to her tzarah. Eishes Ach, however, is a pure issur—and precisely the issur overridden by yibbum. An issur of this type has no koach to generate a ptur for another woman.</p><p><br /></p><p>Accordingly, even when the first tzarah becomes Eishes Ach, she remains within the realm of issur and cannot affect her fellow co-wife. Without the pasuk, the Tzaras Tzarah would remain permitted. The pasuk is thus indispensable.</p><p><br /></p><p>This episode articulates Rav Akiva Eiger’s kasha and Rav Nachum’s yesod as two sides of the same structure, defining why only an ervah—through ptur—can extend to a tzarah, and why Eishes Ach cannot.</p>