Dante Alighieri (1265-1321) maintained that translation destroys the harmony of poetry. Yet his Commedia has been translated into English time and again over the last two-and-a-bit centuries. At last count, one-hundred and twenty-nine different translators have published at least one canticle of the Italian masterwork since the first in 1782, and countless more have translated individual cantos. Among them there are some of the finest poets in the English language, including Robert Lowell and the Irish Nobel Laureate Seamus Heaney. Smith and Sonzogni have assembled and annotated two...