Like other aspects of Roman life, sexuality was supported and regulated by religious traditions, both the public cult of the state and private religious practices and magic. Sexuality was an important category of Roman religious thought. The complement of male and female was vital to the Roman concept of deity. The "Dii Consentes" were a council of deities in male–female pairs, to some extent Rome's equivalent to the Twelve Olympians of the Greeks. At least two state priesthoods were held jointly by a married couple. The Vestal Virgins, the one state priesthood reserved for women, took a vow of chastity that granted them relative independence from male control; among the religious objects in their keeping was a sacred phallus: "Vesta's fire ... evoked the idea of sexual purity in the female" and "represented the procreative power of the male". The men who served in the various colleges of priests were expected to marry and have families. Cicero held that the desire "(libido)" to procreate was "the seedbed of the republic", as it was the cause for the first form of social institution, marriage. Marriage produced children and in turn a "house" "(domus)" for family unity that was the building block of urban life.