Sex without passionate attachment produces a superior form of pleasure free of uncertainty, frenzy, and mental disturbance. Lucretius calls this form of sexual pleasure venus, in contrast to amor, passionate love. The best sex is that of happy animals, or of gods. Lucretius combines an Epicurean wariness of sex as a threat to peace of mind with the Roman cultural value placed on sexuality as an aspect of marriage and family life, pictured as an Epicurean man in a tranquil and friendly marriage with a good but homely woman, beauty being a disquieting prompt to excessive desire. Lucretius reacts against the Roman tendency to display sex ostentatiously, as in erotic art, and rejects the aggressive, "Priapic" model of sexuality spurred by visual stimulus. Stoic sexual morality In early Stoicism among the Greeks, sex was regarded as a good, if enjoyed between people who maintained the principles of respect and friendship; in the ideal society, sex should be enjoyed freely, without bonds of marriage that treated the partner as property. Some Greek Stoics privileged same-sex relations between a man and a younger male partner (see "Pederasty in ancient Greece"). However, stoics in the Roman Imperial era departed from the view of human beings as "communally sexual animals" and emphasized sex within marriage, which as an institution helped sustain social order. Although they distrusted strong passions, including sexual desire, sexual vitality was necessary for procreation. Roman-era Stoics such as Seneca and Musonius Rufus, both active about 100 years after Lucretius, emphasized "sex unity" over the polarity of the sexes. Although Musonius is predominately a Stoic, his philosophy also partakes of Platonism and Pythagoreanism. He rejected the Aristotelian tradition, which portrayed sexual dimorphism as expressing a proper relation of those ruling (male) and those being ruled (female), and distinguished men from women as biologically lacking. Dimorphism exists, according to Musonius, simply to create difference, and difference in turn creates the desire for a complementary relationship, that is, a couple who will bond for life for the sake of each other and for their children. The Roman ideal of marriage was a partnership of companions who work together to produce and rear children, manage everyday affairs, lead exemplary lives, and enjoy affection; Musonius drew on this ideal to promote the Stoic view that the capacity for virtue and self-mastery was not gender-specific. Both Musonius and Seneca criticized the double standard, cultural and legal, that