Commentary Par I 67-72

Glaucus's transformation, described by Ovid (Metam. XIII.904-968), is a dazzling rendition of how an ordinary fisherman, chancing upon a magic herb, is metamorphosed into a god of the sea.  Dante can sharply reduce the poetic space he devotes to the Ovidian scene because it is so familiar to his readers (at least the ones he most cares about).  For the classical history of Glaucus as it comes into Ovid, Dante's primary source, see Diskin Clay (Clay.1985.1).

For Dante's Glaucus (along with Marsyas) as figures of Dante's own divinization, see Rigo (Rigo.1994.1), pp. 109-33.  For the theme of deificatio in St. Bernard's De diligendo Deo as clarifying Dante's notion of 'transhumanization,' see Migliorini-Fissi (Migl.1982.1); she indeed sees traces of Bernard's work throughout the poem, as does Mazzoni (Mazz.1997.1), esp. pp. 178-80, 192-230.

Brownlee (Brow.1991.1), p. 213, suggests that the transformation of Marsyas figures the transformation of the poet, while that of Glaucus has the same function for the protagonist.  Gragnolati (Grag.2005.1), p. 173, is of the opinion that Dante wants us to conclude that, as Glaucus leapt into the sea with his body in Ovid's account (Metam. XIII.949-951), so the protagonist ascended in his flesh.  See Hollander (Holl.1969.1), pp. 216-20, 228-29, for an examination of the Ovidian passage with particular emphasis on the special pertinence of its numerical components (nine and one hundred) for Dante.