An online version of “Copies and Models in Horace Odes 4.1 and 4.2,” an essay published over 20 years ago in Classical World 87, is now available at the CHS website. In the 2015 edition, Gregory Nagy has added translations of the Latin and Greek and has provided additional observations.
Nagy focuses his research on the key word mimesis, explaining how Horace highlights conceptions of mimesis through his poetry:
§3. This idea of mimesis, which I write without italics from here on, works on the principle that those who re-enact something are not only imitating a model: by re-enacting they also become models in their own right, to be imitated by a series of successors who perpetuate, moving forward in time, the chain of re-enactment. I suggest that Horace has achieved an imaginative repetition of this idea in the poetics of Ode 4.2—and of Ode 4.1 as well.
Concurrent with the publication of this essay, Nagy continues to explore the Odes of Horace in his 12.31.2015 Classical Inquiries post, “Some imitations of Pindar and Sappho by Horace.”