A man stands before a glass in a witch’s kitchen and cannot look away, for the mirror is showing him not his own face but the most beautiful woman in the world. The scene is Goethe’s Faust: A Tragedy (its First Part published 1808), in Bayard Taylor’s verse translation of 1870–1871. Faust, waiting among the witch’s beasts, is caught by the mirror mid-turn — “What do I see? What heavenly form revealed” “Shows through the glass from Magic” — and there swims up before him “A woman’s form, in beauty shining”. He gazes on, helpless; the stage directs that “Faust gazes continually in the mirror” while Mephistopheles lounges and jokes, and Faust can only say that “My bosom burns with that sweet vision”. Later he begs, “One rapid glance within the mirror give me”, and Mephistopheles, aside, lets the trick slip: the potion he is about to pour will make “Each woman beautiful as Helen”. The magic mirror has planted a longing the whole tragedy will spend itself pursuing; in the Second Part (published 1832), gazing on Helen herself, Faust knows the vision “That from the magic mirror so enraptured” was only its forerunner, “Was but a frothy phantom of such beauty”.

A second tradition turns the same object from a window on desire into a window on knowledge. In The Hermetic Museum, Restored and Enlarged (the Latin collection enlarged in 1678; this English translation 1893), the personified Sulphur, once freed from his bonds, rewards his deliverer: “He also gives to him a magic mirror, in which” the three parts of the world’s wisdom may be seen “and known at a glance”, and “this mirror clearly exhibits the” creation of the world, the motions of Sun and Moon, and the virtues of every herb. Between them the two witnesses hold the mirror’s double promise: it can show you the one face you will ruin yourself to reach, or the whole order of nature at a look. When a mirror will only ever return what you most desire to see, is it revealing the world, or revealing you?