The poem opens in a green valley, and that image is really crucial for establishing the mood at the beginning. We tend to have such cheerful, happy associations with green valleys that it's hard to imagine anything bad happening there—and for a while, at least, nothing does. Finally, though, the happy story of the valley gets quite a bit darker, setting up a stark contrast that makes the impact of the poem's conclusion all the more forceful.
- Line 1: Here's the happy first appearance of the valley. It's actually the first real image we get in the poem, and it's a pretty pleasant one. It also seems to us that calling it the "greenest" valley is maybe a little bit of a poetic exaggeration (also known as hyperbole). How would you even know which of "our valleys" was greenest? Measure with a color ruler?
- Line 17: Here the speaker just comes out and calls this a "happy valley." Now it's even clearer that the image of the valley is here to make us feel good, to reinforce our positive feelings about the way the palace used to be. Be sure to notice the enjambment, too (that's the way this sentence is cut off by the end of the line). Poe uses that particular technique like it was going out of style.
- Line 41: Ugh. Suddenly this valley's not such a happy place. It's not clear if the valley itself has changed, but its main feature—the palace—sure isn't what it used to be. We also think it's significant that people going through the valley used to be called "wanderers" (17) but now they are "travelers," which sounds a lot less relaxed to us.