A man has been released from prison, but the poem suggests he has been left almost erased. He is "now nothing," and all that remains of him is "the print of a wing," a faint mark where prison hurt him. The image is odd and tender: a wing implies a bird, something meant for flight, now reduced to a trace, like the imprint a bird leaves on a windowpane.
The second stanza turns to escape. He has had "no opportunity yet" to flee in the night, and then the poem twists: the night "was the state." The darkness he might hide in is the same thing that confined him, so even freedom feels watched or owned by authority. Judging by these lines, the speaker seems to feel sympathy mixed with unease. The mood is quiet, bleak, and haunted. Release hasn't brought relief, and the shadow of the system still hangs over everything.