In Book IV ofParadise LostSatan undergoes a metamorphosis in three stages: between his entry into the garden and his discovery by Ithuriel and Zephon he appears as a cormorant (l.196), as a variety of “those four‐footed kinds” (l.397), and finally as a toad (l.800). Ann Grossman has recently claimed that such animal imagery implies “a medieval treatment of evil as grotesque,“ and Irby Cauthen has shown—most notably from Topsell'sHistorie of Serpents—how appropriate it was for a seventeenth‐century poet to portray Satan as a toad. What I would like to do here, far from contradicting either of these helpful essays, is to consider what may have been the theological basis for Milton's presenting Satan's decline in Book IV as he does; and this, I believe, will allow a clearer understanding of how Satan's metamorphosis—particularly as a toad—not only enhances the account of what Gossman aptly terms his “progressively degenerating hell of self,“ but also in so doing reinforces the poem's pervasive theme of the just