Reality Ensues: This episode is a Deconstruction of a common plot in Star Trek—a long-standing medical problem is cured by the miracle of Starfleet medicine. More likely, a disease that has gone uncured for so long won't be so easily resolved—and indeed, Bashir never finds the cure he hoped to find. He still has more success than anyone before, but the full benefits of his discovery won't be felt for another generation or so.
What the Hell, Hero?: Dax gives a beautiful one to Bashir, telling him that it's pure arrogance to think that there isn't a cure for the Blight simply because he couldn't find it. Funnily enough, this is in the wake of Bashir chastising himself for arrogance of a different kind—thinking that he could find a cure so easily for a disease that had gone uncured for so long.