When we talk about fan fiction, we rarely think: “John Milton”. And yet, how better to approach his Paradise Lost (1667), which takes Satan (barely mentioned in the Bible) and makes this fallen arch-fiend into an ambivalent, epic hero? Structured on techniques and themes borrowed from Virgil’s Aeneid, Ovid’s Metamorphoses, Dante’s Divine Comedy, Spenser’s The Faerie Queene, and countless other texts and genres, Milton remixed classical and Renaissance forms to fashion the biblical universe into a setting for English literature’s (perhaps) greatest poem, one which Philip Pullman believes will [“n]ever be surpassed”.

And if Milton stoked fandom in turn, he had no keener admirer than William Fairfield Warren, an eclectic scholar and the first president of Boston University. By the time Warren wrote his last work, The Universe as Pictured in Milton’s Paradise Lost (1915), he had already made his name by claiming to have discovered the location of Eden. Warren’s Paradise Found: The Cradle of the Human Race at the North Pole (1881), a study that “positively reeked with academic authority”, argued (across five-hundred, heavily-footnoted pages) that our lost Terrestrial Paradise was once catty-corner to Santa’s workshop.

In his final work, Warren turned his attention from Eden to Hell and became a cartographer of the poetic imagination. The pursuit makes counting pin-dancing angels sound like schoolhouse addition. Trying to deduce how Milton intended us to envision the “circumfluous waters calm, in wide / Crystalline ocean” — the poet’s elaboration on God’s creation of a firmament in Genesis — Warren writes that the “Avestan picture of the unitary water-circulation of the universe as the Iranians conceived it presents a most interesting parallel”. Why, but of course. One of the many pleasures in reading this book comes from the presumption of its subtitle: “for personal and class use”. Warren breezily dissects esoterica gleaned from Zoroastrian mysticism, the Sanskrit Rig Veda, and Homeric allusion, never pausing to question if his student-reader can follow.

And he grants Milton the same generous benefit of doubt. Finding an inconsistency between the number of ringing celestial spheres in “On the Morning of Christ’s Nativity” (nine) and Paradise Lost (ten), the scholar explains that this point of discrepancy in Milton’s Ptolemaic cosmos is moot because “the music of the spheres was produced by the motion of the divinely attuned material spheres, and that the tenth was soundless because by nature immaterial.” Like the poet he admires, Warren will move earth and heaven in his quest for subtle harmonies.

Warren was not the first to map Milton’s “facile gates of Hell too slightly barred”. In an appendix to his study, the professor includes diagrams by David Masson, John Andrew Himes, Thomas N. Orchard, and other predecessors. Taken together, they offer whimsical schemata for how to best imagine the realms of chaos, night, and empyrean heaven. A frequent subject for visual artists (notably John Martin, “a Geordie ingénue with a chip on his shoulder”, who transposed Adam and Eve into the sublime settings of romanticism and swapped Milton’s republicanism for the revolutionary politics of his own time), Paradise Lost demands to be seen.

But Warren had something in mind beyond illustration. There is an ethical dimension to his form of reading. Describing how “[m]yopic interpreters of the Odyssey, possessed of no imagination, have for centuries tried to find Homer’s world within the narrow limits of Hellas and the Levant”, he believes that poor readers have not only “done violence” to poetry, but, as teachers, become “blind leaders of the blind”. There is a knowing irony here. Like Homer, Milton had lost his sight by the time he composed his epic. In order to regain an accurate vision of Paradise Lost, Warren thinks we need to learn to see anew.