Metamorphoses Book 2: Mercury and Battus
Chiron had called out to Apollo to help his daughter, but Apollo was in a far away pasture disguised as a shepherd and thinking thoughts of love. While he was thus distracted, the flock in his charge wandered away. Mercury, prankster of the gods, stole the herd and drove them into the woods where they were hidden from their shepherd. The only witness to his action was an old man named Battus, which meant "chatterbox." Mercury offered the old man a cow for his silence, and the man assured him that a stone would speak sooner than he would. To test him, Mercury pretended to leave and then disguised himself. He returned to Battus and offered him a cow and a bull for information on the missing herd. The man quickly complied without realizing the trick, and in punishment for his betrayal, Mercury turned Battus' heart to stone.