"The Love Song of J. Alfred Prufrock" begins with an epigraph which is taken from Dante's Inferno. These lines in Italian are from Canto XXVII. Here is the translation:
If I thought that I was speaking
to someone who would go back to the world,
this flame would shake no more.
But since nobody has ever
gone back alive from this place, if what I hear it true,
I answer you without fear of infamy.
In this Canto, Dante speaks with Guido da Montefeltro, who is wrapped in flame. Montefeltro had sinned in life by conspiring with Pope Boniface VIII. In the Canto, Guido (speaking through flame) agrees to tell his sins to Dante because he believes that no one, Dante included, could return to the world and perhaps tell others of his sins. Had Montefeltro known Dante could return, he might never have shared his tale.
In Eliot's poem, Prufrock speaks with the knowledge that his words will not be repeated. Some critics say that this poem is an interior monologue, that Prufrock is speaking or thinking to himself. Eliot has indicated that the "you" in the poem is an unidentified male companion. In the case of the former, Prufrock is comfortable to admit his flaws and self-deprecations because he is not divulging anything to another person. If he is speaking to some companion, perhaps he felt that this male companion would not repeat what he says. Montefeltro confessed his tale to Dante under the assumption that Dante could not possibly leave Hell and return to Earth; thus, Dante could not repeat Montefeltro's confession to others. Likewise, Prufrock speaks with the same understanding (whether as interior monologue or if he'd been confiding in a friend) that his words would not be repeated. In both cases, these men fear embarrassment and damage to their reputations.