The Monument (Symbol)
When the speaker imagines the shade wandering Dublin, he speculates that it might go to visit the monument honoring Parnell. A moment later, though, the speaker pauses to wonder whether the sculptor of the monument has been paid yet. This monument symbolizes Parnell's complicated legacy within Dublin. To an extent, he is revered and beloved—after all, the city contains a monument to him. However, his reputation is somewhat neglected, Yeats hints. The possibility that the speaker remains unpaid suggests not only that Parnell himself is somewhat forgotten, but also that the same social distrust that originally destroyed Parnell's reputation in Dublin has continued to grow—causing basic elements of the social contract—like paying craftsmen for their work—to be abandoned.
The Sea (Symbol)
The sea symbolizes life and engagement with the living. When he imagines the shade returning the Dublin, the speaker pictures him visiting the sea. The image of the shade breathing in the sea's salty air is a particularly vivid, sensory evocation of embodied existence, showing clearly that the shade is back in the world of living things despite his ghostliness. At the same time, the sea, an element of the natural world, contrasts with the gossipy viciousness of Dublin's social life. While the sea represents all that is satisfying about the return to life, it is ultimately overpowered by the cruelty of human beings. As a result, the speaker tells the shade that he must return to death, and give up the chance to smell the sea.