When we speak of "In Medias Res", we are referring to the way a story is constructed and then told to the public - to its structure. It is a Latin expression that means "in the middle of things", and it is at this point that a story begins when using this narrative technique: in the middle. In the case of this excerpt from "The Irony" the chronological order of events is broken, and the spectator is thrown at a time when events are already under way.
The invocation to the muse, in this excerpt, expresses in a dramatic way the grandiosity of the subject to be sung, conferring to the composition of an inspiration honored by the poet.
