me as a substitute for Ganymede". It was a longstanding if infrequent theme in Latin satire; one of the few surviving fragments of Lucilius, Rome's earliest satirist, jokes about a personified penis (Mutto) whose girlfriend Laeva ("Lefty") wipes away his "tears". A graffito from Pompeii reads "when my worries oppress my body, with my left hand I release my pent-up fluids". The etymology of the Latin verb masturbari is unclear. It has been argued that it is a compound of turbare 'agitate' and mas 'male', in an otherwise unattested usage for 'penis'. One traditional view sees man(u)- 'hand' with an altered form of stuprare 'to defile, commit a sexual wrong against'. Calvert Watkins proposed that it derives from a Proto-Indo-European root meaning 'marrow, brain', since ancient medical writers believed that semen descended from the brain through the bones; if this is correct, the word turbare may still have influenced the formation in Latin. Bestiality The mythological tradition is full of sexual encounters between humans and animals, especially mortal women and gods in the guise of animals. Bestiality is a particular characteristic of intercourse with Jupiter (Greek Zeus), who visits Leda as a swan and Europa as a bull. The Minotaur is born when Pasiphaë feels such sexual attraction for a bull that she has herself disguised as a cow to mate with him. Satyrs, known for their sexual voracity, are often pictured with bestial features. Mock bestiality is recorded as a form of sexual roleplay in Imperial Rome. Nero is supposed to have enjoyed a form of bondage with either male or female partners in which he dressed in animal skins to attack their genitals, just as condemned prisoners were bound and attacked by wild animals in the arena (see Damnatio ad bestias). The historian Dio tells of how a prostitute pretended to be a leopard for the gratification of a senator. The actor Bathyllus was known for an erotic dance in which he dressed as Leda having sex with the swan; the women watching were variously aroused. Bestiality is also a theme of Apuleius' novel Metamorphoses (or The Golden Ass), in which the protagonist, transformed into a donkey, is desired by a wealthy noble matron, just as Pasiphaë desired the bull. There is some indication that violent sexual encounters, like other mythological scenarios, were acted out as punitive entertainments in the arena. The poet Martial praises a scenario for