The speaker of "Parting at Morning" is not one of those overly descriptive or ornate dudes you might find in old school poetry. Nope, this guy likes things short and simple. He says what he needs to say in only four lines, and he says it in a rather succinct and rhythmic way. And since he speaks with a first-person point of view, we also know that he's sharing his morning after experience in a personal way—without giving too many intimate details, thank goodness.
In lieu of intimacy, the speaker uses nature and the poem's setting to reflect the way he feels as the sun paves the "path of gold" that illuminates his need of a "world of men." We round that corner with him right at the beginning of the poem and experience the dawn of morning in the same sort of sudden way that he does. His use of syntax ("Round the cape of a sudden") helps us understand his feeling of suddenness without using too many words. In that sense, we lucky ducks get to experience everything (well, almost everything) with the speaker, which gives his voice a kind of immediacy that sounds like a fresh new morning.
The speaker's neat little rhymes also make the poem sound fresh and upbeat, just like morning. And since each rhyme at the end of every line is a short and stressed syllable, we hear that upbeat sound even more. The speaker doesn't hover over his words too much. Instead, he kind of skips us along from point to point. After all, this guy has things to do and places to go, so it makes sense that we wouldn't hear a voice that's quiet and sleepy.