The shape is a stubborn apprenticeship: a mortal coaxes a magician's secret out of him and holds onto it against the magician's will. The served witness comes from the seventeenth-century collection Liao chai chih i, the tales Professor H. A. Giles turned into English as Strange Stories from a Chinese Studio, and follows a Ch'ang-an scholar named Chia Tzu-lung and his aloof neighbour, Mr Chên. Whenever Chia needs money, Mr Chên brings out a black stone and, "muttering a charm," rubs it on a tile or brick, which is "changed into a lump of silver." The stone, it emerges, holds the power of "changing anything into gold" — an art Mr Chên guards as "a secret known to the Immortals only".

From there the story becomes a slow siege for the power itself. Chia tries once to steal the stone outright and forfeits the friendship; finding it again by the riverbank, he bargains not for a lump of silver but for the words, pressing his friend to "teach him the formula". Mr Chên, afraid that conferring such a gift on a mortal will bring Heaven's punishment down on him, resists and then relents — whereupon Chia turns a whole stone washing-block to silver at a stroke. Only at the last does the magician confess what he has been all along: "a fox who, by a sinless life," has reached "the truth which leads to immortality."

This telling reaches the shelf through the 1922 compilation Myths & Legends of China, which relays Giles. The record files the same passage of magic from magician to mortal among Icelandic, English (an Arthour and Merlin), Lappish, Jewish, and Indian shelves as well, but only the Chinese witness is wired to served text; the others wait unread. If the secret can simply be taught to anyone stubborn enough to ask for it, what is left to separate the magician from his pupil?