We think of this echo-y poem as being primarily about sound, since most of the poem describes those reverberations of a bugle in a valley. But the very first line of the poem describes the effect of light slanting through a valley against a castle, so light must be pretty important, too. Since we know that the light is coming in at an angle, we know that the poem probably takes place at sunset, so the light, like the echoes, is also fading away and "dying." This seems appropriate (if kind of a downer), since the larger question that the poem asks us is about the kinds of "echo" that we might leave when we die. The echoes fade, the light is fading, and everyone dies. Again—not to bum you out or anything.
- Line 1: The famous first line of the poem doesn't make a lot of sense at first glance. We're used to thinking of "splendour" as meaning "gorgeous, brilliant appearance," but it can also be used to mean "bright light." So this is an example of a familiar word being used in an unfamiliar way.
- Line 3: How can light "shake"? This must be a metaphor to describe the visual effect of the way that light shimmers and glistens on the surface of a lake, particularly when the sunlight is coming in at an angle. The speaker also uses alliteration when he repeats the first (L) sound of the words "long light."
- Line 11: Here's another strange image: the "purple glens." Aren't glens, or valleys, usually green? This is another trick of the light at sunset or sunrise—the angled light makes things take on a purplish or reddish color.