A prisoner who cannot walk out of his cell slips out of his own body instead. In the Kalevala (Finnish oral song compiled 1835–1849), the old singer Wäinämöinen has been lulled to sleep in Manala, the death-land, and while he sleeps a wicked wizard sets "a thousand nets of copper" across the black river to hold him there forever. Waking and sensing the trap, the singer does not fight the meshes; he simply ceases to be a man. He "Changes too his form and feature", he "Slips into another body", and then he is gone through the water "Like a serpent in a circle" — the witness sees him "Crawls he like a worm of magic" straight through the copper and the interlaced iron. When the wizard hauls his nets at dawn he finds only fish and serpents; the hero, meanwhile, gives thanks that he has "Had escaped from Tuonela". Escape here is not an act of strength but of self-erasure: the shape that was captured is exchanged for one the nets were never built to hold.

The same trick recurs half a world away, in a compilation of Chinese myth published in 1922, where the monkey Sun is shut with his master inside a locked cupboard that robbers carry off into the night. Cornered, he promises "I will save you yet", then narrows himself past every wall: he "changed himself into an" ant and "escaped from the cupboard", leaving the lock and the box intact behind him. In both stories the container is sound and the guard is competent; what fails is the assumption that the thing imprisoned will keep the shape it had when the door was shut. Thompson filed the pattern under transformation undertaken to break out of captivity, alongside an Italian witness our shelf has not yet opened.

If a prison can only hold the body a captive happens to be wearing, what exactly were the walls ever holding?