The epigraph to “The Love Song of J. Alfred Prufrock” comes from Dante's Inferno, a work of literature that had particular resonance for T. S. Eliot throughout his life. The words are spoken by Guido da Montefeltro, a character stuck in the eighth circle of hell for all eternity:

If I but thought that my response were made
to one perhaps returning to the world,
this tongue of flame would cease to flicker.
But since, up from these depths, no one has yet returned alive, if what I hear is true,
I answer without fear of being shamed.

Essentially, what this means is that Guido feels able to tell his story to Dante's protagonist—a fictional version of Dante—because he is sure that the poet will never leave hell and so will be unable to tell anyone else about all the horrible things Guido did that put him in hell in the first place. Guido, however, is profoundly mistaken. Dante is indeed passing through, and he will eventually make it out of hell and tell the story of what this wicked man did when he was alive.

The relevance of the epigraph to “The Love Song of J. Alfred Prufrock” is not immediately apparent. It seems to be the case that Prufrock believes that by singing his song, no one else will ever hear it. It is as if he were sharing a confidence with the addressee—who is arguably himself—about all his insecurities, neuroses, and anxieties, safe in the knowledge that no one will divulge the information.

One could also say that Prufrock, like Guido from Inferno, lives in a kind of hell from which it is impossible for him to escape.