T he gist of an old joke—it has a dozen local iterations—is that the Loeb Classical Library translations are so baffling that you have to consult the original Greek or Latin on the left-hand page to decipher the English translation on the right.

Funny or not, the wisecrack catches the condescension long directed at the Loebs, that venerable series of Greek and Latin classics in uniform volumes with facing English translations. Professors of classics in particular used to frown upon them. Until recently, merely to be seen on campus with a Loeb was to court scandal. There were gradations of disgrace. Those Loeb editions of Boethius, Bede, and Augustine I saw on the shelves of the professor who taught me Anglo-Saxon: those were permissible for an English scholar. But I, as a classics major, was to eschew the very same volumes. Even as an undergraduate, though I prized my Loeb edition of The Republic, edited and...