Sexuality was a "core feature" of ancient Roman slavery. Because slaves were regarded as property under Roman law, an owner could use them for sex or hire them out to service other people. Some scholars propose that content in Cicero's letters indicate he had a long-term homosexual relationship with his slave Tiro. As Eva Cantarella stated bluntly, "the Roman "paterfamilias" was an absolute master, ... he exercised a power outside any control of society and the state. In this situation why on earth should he refrain from sodomising his houseboys?" But this form of sexual release thus held little erotic : to use one's own slaves was "one step up from masturbation". In describing the ideal partner in pederasty, Martial prefers a slave boy who "acts more like a free man than his master", that is, one who can frame the affair as a stimulating game of courtship. When figures identifiable as slaves appear in erotic art, they are performing routine tasks in the background, not taking part in sex acts. In his work on the interpretation of dreams ("c." 170 AD), Artemidorus takes a symbolic view of the sexual value of slaves: to dream of having sex with one's own female slave was a good thing, "for slaves are the dreamer's possession; therefore taking pleasure in them signifies the dreamer's being pleased with his own possessions".