Commentary Par I 68

For Glaucus's 'tasting' of the grass that transforms him as 'reversing' Adam's 'tasting' of the forbidden tree ([Par XXVI 115]), see Rigo (Rigo.1994.1), p. 113.  (The notion of Glaucus as Adam in his refound innocence goes well with that of Dante in his: see Carroll's observation, C.Par.I.55-57.)  We observe here a conflation of Ovid's Heroides (XVIII.160, a verse (cited by Rigo.1994.1, p. 114) referring to Glaucus: 'reddidit herba deum' (whom a plant once deified -- tr. H.C. Cannon).

The two major classical myths evoked in this canto, Apollo and Glaucus, along with the associated references to arrows and the ingestion of food, indicate the two main ways to understanding that we will hear about all through the cantica, intellectual penetration and a more passive reception of the truth.

That Dante has turned to Ovid for three major myth/motifs in this canto (Apollo and Daphne/immortality; Apollo and Marsyas/being drawn out of one's bodily limits; Glaucus/transhumanization) would almost seem to indicate that, for Dante's purposes, Ovid's poem about the gods, transmogrified by Dante's Christian intellect into shadowy prefaces (see [Par XXX 78]) of a higher truth, is a more adaptable source than Virgil's martial epic for this more exalted and final component of the Comedy.  If, after our encounter with the first cantos of Paradiso, we are of that opinion, we are not altogether incorrect.  However, if we believe that Virgil's text is no longer a valued source in the poem's most Christian precincts, we will eventually be disabused of this notion, particularly in Cantos XV and XXXIII.