The poem is strange and dreamlike, and its central image is a kind of journey back into the womb. The speaker "books a passage" in a woman's belly, as if buying a ticket, and the destination is the moon. That mixes two ideas: travelling somewhere far away and being carried inside a body before birth. The title, "Music of the spheres," points to the old idea that the planets make a silent, perfect harmony as they move.
Then the setting shifts. From inside, the speaker hears sound coming "through the ceiling": music, stories of comedies, and the names of the hanged. Judging by the imagery, this could be the muffled noise of the outside world reaching someone still unborn. It is a mix of laughter and death, entertainment and punishment, all heard faintly from below.
The speaker's feelings are not stated outright, but the tone is calm, almost matter-of-fact, which makes the last line land harder. The mood is eerie and quietly unsettling: a safe, enclosed place, with the whole human world, joyful and grim, humming just beyond it.