What are the themes of "Haunted" by Walter de la Mare?

The poem "Haunted," by Walter de la Mare, is similar to its more famous brother "The Listeners" in many ways. De le Mare here, as in "The Listeners," uses vivid and evocative imagery to describe the setting of an abandoned house in the woods; in this poem, the house is explicitly "haunted." As in "The Listeners," the poem is more atmosphere- and mood-based than dependent upon theme.
However, we can isolate a few themes in this poem—similar to those found in "The Listeners."
1. Isolation, or the theme of "one man alone." The speaker in this poem is very much on his own, looking on. He observes the haunted house from the cover of "wood," and the woodland seems busy with the sound of conversation from which he is excluded—a "thin voice piping airs," a "voiceless raven" who, nevertheless, is flying to "her mates," while the speaker is alone.
2. Watching, or invisible observation. In this poem, not only is the speaker describing how he "watched" the windows of the haunted house, but the "West," personified, "shut down a heavy eye," as if it, too, has been watching the scene. Meanwhile, like "last tapers . . . the watch-stars kindled in the sky." This theme of quiet observation lends to the eerie atmosphere of the poem.
3. Mystery and the supernatural. The poet leaves much to our imagination in this poem. We do not know who haunts "the haunted house," but we do hear a mysterious "thin voice piping airs," and "amidst the sedge a whisper ran." The poem is pervaded by the sense that, just beyond the quietude of the central scene, something unknown is lurking.