Dante Alighieri's "Inferno" raised "visual potential" that informed the film. Dantean scholar Amilcare A. Iannucci argues the plot follows the "Divine Comedy" model in beginning with "selva oscura", in Lomax losing his conscience defending a guilty man, and then entering and exploring deeper circles of Hell. Iannucci compares the office building structure to the circles, listing fireplaces where flames are always present; demonic visual phenomena; and water outside Milton's office, analogized to Dante's Satan's icy home, albeit situated at the top of Hell as opposed to the bottom. Free will is also a major theme in the "Divine Comedy", with the film's musings on the concept being similar to Dante's "Purgatorio", 16.82–83 ("if the present world has gone astray, in you is the cause, in you it's to be sought").