After an epigraph from "The Ballad of Sir Patrick Spence," in which the title character sees the new moon as an omen of bad weather, our speaker starts off wishing for the same kind of storm. The tranquil night he's experiencing just won't cut it, and he imagines that the new moon he sees will have the same effect as it did on Sir Patrick—namely, serve as a predictor of bad things to come.
The speaker's hoping that a good storm will shake him out of his numb, depressed state by exciting his emotions. He then addresses someone he calls "Lady," further describing his depression. All he's able to do is listen to the birds and watch the green evening sky. He can see that the clouds, stars, and moon are all beautiful, but he can't "feel" their beauty. The dude is in the dumps.
He goes on to conclude that there's no outside cure for his blues. He notes that the way we see the world is colored by our internal moods. Without love in his life, though, everything around him just looks lifeless and dull.
There is hope for him, however. If he's going to be cheered up, it must come from the soul. That's the source of all the world's beauty and melody. Still, for that to happen, the soul must be filled with joy. Joy has the power to revitalize our energy and make the world seem brand new to us.
Once upon a time, the speaker was able to feel such joy, but now life's hardships have worn him down. Worst of all, he's even lost the power of his imagination. Now, he's left to try to consciously recapture some part of his former joyful, imaginative self in order to escape his depression.
On that cheery note, the speaker turns back to notice that the wind is howling in a terrifying fashion. It's not clear if the wind has actually picked up, or if the speaker's imagination is what's picking up. In any case, the speaker notes that this wind would be more at home on a desolate mountaintop or abandoned witch's cabin.
Eventually, this wind reminds the speaker of some kind of demonic celebration. Then it's like an actor in a tragedy, or a poet telling a story about a little lost girl in the wilderness—not good.
Not surprisingly, the speaker can't sleep, even though it's midnight. He sure wishes that his friend—"Lady"—won't have to go through the same kind of hardships that he's experiencing. In fact, he wishes her rest, health, peace, and joy. She's his number one "friend," after all, and he wants nothing but happiness for her. Now isn't that nice and not at all terribly depressing?