As we have seen, Cadmus and Harmonia end their days as benign serpents -- their final transformation arriving like a teletyped confirmation from -- the gods? Nature? Fate? -- that his revised view of the serpent, i.e. that it was "sacer" - was correct. His metamorphosis gives his reading a sudden legitimacy that otherwise would still be open to question -- almost like an official stamp, or notarization.
As in a dream, his wish is fulfilled:
Cadmus said ‘Surely that snake, my spear pierced, must have been sacred, when, fresh from Sidon, I scattered the serpent’s teeth, a strange seed, over the earth? If that is what the gods have been avenging with such sure anger, may I myself stretch out as a long-bellied snake.’What's curious is that Cadmus is not wishing to become a serpent, but rather to know the truth -- "if" this is the case, "then" let this follow from it. In the world of Ovid, knowing the truth can be literally transformative, but unlike in, say, Plato, it's not necessarily a liberating experience.
Cadmus points up the engima that has haunted his house from the start - the imponderable relation of man, or woman, to "sacer"* - from Actaeon to Semele and even perhaps Narcissus and Echo, the encounter with what is "sacer" has proven to be destructive. It need not always end badly, as Acoetes' tale suggests, but for Pentheus, failure to apprehend Bacchus leads to a terrible transformation.
In this archaic image (550 BC), Cadmus is again fighting the serpent/dragon; behind the creature stands the god, Mars.