Io, daughter of the king of Argos, was seduced by Jupiter disguised as a cloud to conceal this further infidelity from his wife Juno. But the latter was not deceived so Jupiter changed Io into a heifer. Juno cunningly asked for her as a gift which her husband could not refuse. When Juno handed the heifer over to the hundred-eyed giant Argus to guard, Jupiter sent his messenger Mercury to recover Io. Mercury lulled watchful Argus and cut off his head. Juno then took Argus's hundred eyes and, as a memento, set them into the tail of the peacock.