Thursday, February 18, 2010
Another Vergilian expression, tum vates, referring to these prophetesses (Cassandra at 3.187 aut quem tum vates Cassandra moveret? and the Sibyl at 6.582 tum vates sic orsa loqui), is metrically equivalent in the dactylic hexameter to plena deo. Could tum vates have ousted plena deo?
Another possibility is that someone, after Vergil's death, completed one of the half-lines in the Aeneid with words including plena deo, and that such a version was current in Seneca the Elder's day. Aeneid 2.346 is a likely hemistich, as the context involves Cassandra.
In the case of both Cassandra and the Sibyl, the god who inspired them to prophecy was of course Apollo.
Update: See Nicholas Horsfall, Virgil, Aeneid 6: A Commentary (Berlin: De Gruyter, 2013), pp. 627-629.