Why is that everyone in the village died of smallpox, except for the milkmaids, who never got sick? Is this some kind of milkmaid magic? Or is there something in the biographies of each milkmaid that causes them to become... ah, what is the right word? It's almost as if they are, ah, "immune" to smallpox? Is that possible? It's almost as if they get cine (aid) from the cows (vacca). One wonders if we could deliberately give this vacca-cine to people?