[Roman Marriage Vows depicted on the Sarcophagus of the Dioscures, late 4th century]
[Photographed by Ad Meskens, Source: Wikimedia Commons]
[Image of Modestinus in the main reading room of the Supreme Court Library]
[Source: The Oyez Project]
*A dowry was also generally required for a wife but not for a concubine. This, however, seems not to have necessarily been a legal requirement but a social one as far as I can tell.
Further Reading:
Women of History: Concubines
Sources:
Lefkowitz, Mary R. and Maureen B. Fant, trans. Women’s Life in Greece and Rome: a Source Book in Translation. Baltimore, MD: Johns Hopkins University Press, 1992.
Rawson, Beryl. “Roman Concubinage and other De Facto Marriages.” Transactions of the American Philological Association 104 (1974): 279-305.
Treggari, Susan. “Concubinae.” Papers of the British School at Rome 49 (1981): 59-81.