Parashat Va'Era 5772: Call A Dermatologist

In Exodus 9:10, the Torah refers to the plague of boils as "avabu'ot poreiakh," which means "an inflammation breaking out."  In the Talmud (B. Baba Kamma 90b), Rabbi Yehoshua ben Levi says that the boils that the Egyptians had on their skin were moist on the outside and hard on the inside.  This is the opposite of normal boils, which are hard on the outside and contain liquid pus on the inside.

The Torah Temimah says that Rabbi Yehoshua ben Levi's interpretation is necessary because if the boils were ordinary, they wouldn't really count as a plague.  Boils come and go, sprout and heal. In fact, he notes that only a boil that is wet on the outside and dry on the inside disqualifies the firstborn animal sacrifice; a regular boil is not a big enough defect to matter. Torah Temimah says that these "wet on the outside and hard on the inside" boils are the "Egyptian boils that do not heal" mentioned as a divine punishment in Devarim 28:27.