It hangs from a chain in a museum case in Hannover, small and bronze and entirely matter-of-fact about what it is. A winged phallus with bird legs, the feet fitted with tiny rings that once held bells. The wings spread to either side. The whole object was designed to move — to hang in a doorway or above a cradle, to swing in a draft, to catch the light and ring softly when the air shifted. This is a fascinum, the primary Roman protective object against the evil eye, and it was as ordinary a household item in imperial Rome as a smoke detector is today: unremarkable in its presence, urgently necessary in its function, noticed only when it was absent.