unde vocalem temere insecutae
arte materna rapidos morantem
fluminum lapsus celeresque ventos,
blandum et auritas fidibus canoris
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 ...