Yeats likes to work behind-the-scenes to make his poetry have a particular sound. His lines are embedded with conscious meter, rhyme, and wordplay, which make for a musical experience. "Adam's Curse" is written in heroic couplets, which are pretty old-school. But W.B. manages to keep it fresh each time. Check out "Lake Isle of Innisfree" and "Leda and the Swan" to see some variations of his line-crafting. Who said poetry isn't hard work?