The title, “Mezzo Cammin,” takes its name from the first line of the Inferno. Longfellow, the first American to translate Dante’s Commedia into English, “was 35 when he wrote this poem, halfway through the scriptural lifespan of 70 years.”
Additionally, Longfellow wrote six sonnets, entitled “Divina Commedia,” which were composed during the grief-filled aftermath of his second wife’s death.
“The six sonnets. . .were written during the progress of Mr. Longfellow’s work in translating the Commedia, and were published as poetical fly-leaves to the three parts. The first was written just after he had put the first two cantos of the Inferno into the hands of the printer. This, with the second, prefaced the Inferno. The third and fourth introduced the Purgatorio, and the fifth and sixth the Paradiso.”    —Representative Poetry Online (retrieved on July 7, 2009)