The poem begins with a classroom exercise: students of psychopathology are told to imagine a safe place and go inside it. The speaker tries the usual choices, such as a home, a room, a forest, a cave, but they vanish quickly. Instead the mind enters a prison cell, with dirty whitewashed walls, an iron door and a big key. Strangely, the speaker feels safe there and sleeps, while shadows of inmates drift past.
Then a voice calls the speaker back to the present. Tears fall from closed eyes, and the speaker hides them. On opening their eyes, the speaker sees that the mind has gone to the cell, and this breaks the heart. The poem asks why the mind would pick that place as an escape, since it was the very place of near death.
The mood is heavy and haunted. The speaker says the choice was not theirs, and that dark days and nights have stretched out a "life of death." Memory will not let them forget. The awkward, broken phrasing seems to echo the pain of the memory itself.