arte materna rapidos morantem
fluminum lapsus celeresque ventos,
blandum et auritas fidibus canoris
ducere quercus.
Context: It appears that Horace mentions one after the other possible songs and singers to consider whether each is adequate to praise Caesar Augustus. In these lines he describe’s Orpheus.
I get a general idea of these lines: Orpheus’s singing is so powerful that the woods followed along after him, while it holds back the tearing force of the rivers, and the swift winds; he coaxes the oaks who prick up their ears at his tuneful lyre.
Questions:
vocalem: is this to be taken substantively as the subject of the present participle morantem?
Orphea: how does this fit it? Does it agree with arte materna?
blandum: is this like vocalem to be taken substantively, as subject of the infinitive ducere?
The key here is that Orphea is the Greek accusative of Orpheus, the object of insecutae [sunt], not an adjective formed from Orpheus’ name. The words vocalem, morantem and blandum are accusatives in agreement with Orphea.
N.B.: Orphea can’t be in agreement with arte materna because the -a of Orphea is short. arte materna is ablative, and the -a of materna is long.
blandum + infinitive is a syntactic stretch, i.e., poetic license: “alluring to lead”. See Lewis & Short, blandus: