The action proper begins with the second stanza.

The soul of the dead woman taps at the window in the shape of a night-butterfly or moth--imagining, perhaps, that she has still a voice and can make herself heard by the man that she loves.

She tells the story of her wandering in space--privileged to pass to heaven, yet afraid of the journey.

Now the subject of the poem which the lover happens to be writing inside the room is a memory of the dead woman--mourning for her, describing her in exquisite ways.

He can not hear her at all; he does not hear even the beating of the little wings at the window, but he stands up and opens the window--because he happens to feel hot and tired.