Surgery is the subject here, but the poem reads less like a hospital scene than a dream of one. The speaker describes being operated on in strangely domestic terms: a carpenter "made an end of my door," and a surgeon arrives carrying "a barrel of lemons." The door suggests a boundary being finished or removed, so the body becomes a house whose entrance is gone.
The surgeon's trip "to the exchange" gives the operation a faintly commercial feel, as if the body were something traded or bargained over. Then comes the sharpest moment: the surgeon "broke me where / I had not been." The speaker is opened in a place they have never reached themselves. The last line, "so fresh was the night within me," suggests an inner darkness that is new and untouched.
The mood is odd, vivid and a little unsettling. The speaker sounds calm and almost wondering rather than afraid, as though being cut open reveals something unknown inside.