"If the poet is primarily concerned with earth—with displaying particular being and concrete reality—he will tend to conceive of poetry as a passive art, concerned with perception and preservation. ... If, on the other hand, the poet is more concerned with world—with the historical, mythic, and spiritual context that the poem creates or invokes—he will tend to see poetry as an active art, and in some sense even a domineering one."
This is a very thought-provoking piece, well worth reading and pondering. I am myself always uncomfortable with dichotomies and I am sure Kirsch does not mean that the two poetries are altogether mutually exclusive. I also think that Heidegger's oracular preferences and predilections may make him somewhat insensitive to pure song.