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.