Sin and her incestuous partner Death pose one of the most tenacious problems in Milton criticism. Samuel Johnson pronounced them “one of the greatest faults of the poem.” The problem is twofold. First, as obvious allegorical personifications, they seem inconsistent with the rest of poem. Maureen Quilligan believes that the allegorical passages in books three and ten “bracket” the heavenly and edenic scenes as a way of signaling that these passages are themselves mediated and not as directly mimetic as they might otherwise appear. Stephen Fallon cleverly asserts that Milton uses personification as a figure for the theological belief that evil is the privation of good, based on the assumption that personifications have no “ontological status.” Catherine Gemelli Martin believes that the interweaving of personification awith verisimilar representation is analogous to the conflict occurring in the seventeenth century between the medieval worldview, based on accordances, and more modern empiricism, and that it adds to the “chiaroscuro” of Milton's baroque allegory.

Of all these critical treatments, only Martin is willing to entertain the idea that Sin and Death are at least a part of Paradise Lost's spectrum of representation and therefore not wholly inconsistent with the rest of the poem. In order to make this argument, however, she must posit that seventeenth-century allegory generally and Paradise Lost specifically is a radically new genre, bearing little relationship with what she calls the “normative” allegory of Spenser.