Semo Sancus, the God of Oaths

Gregory DiPippo

Yesterday, we mentioned the god Semo Sancus in connection with the legend of Simon Magus, since St Justin Martyr mistook a statue of the former on the Tiber Island for the latter. The cult of this god is believed to have been imported into the religion of Rome from Umbria, the region immediately to the north of Latium. Cato the Elder, the very first Latin historian, and Silius Italicus, a writer of the later 1st century, both say that he came from the Sabines, who lived to the north of Rome, and was the father of the hero Sabus from whom that people took its name.

Sancus’ role was to protect and act as the guarantor of oaths regarding various activities such as marriage, commerce and hospitality. His name is connected to the verb “sancire, sanxi, sanctus”, which has a very wide range of meanings: to establish, appoint, decree, ordain, especially in regard to oaths and laws; hence also, to enact, confirm, ratify; in a religious sense, to make inviolable, when the standard meaning of the participle “sanctus – holy.” The adjective “sacer – sacred” is derived from the same root “sac-”.

He is frequently associated with other gods who served the same role as guardians and guarantors of oaths, especially Jupiter, the protector of hospitality, Mars, and Hercules, the guarantors of military oaths. To words “Dius Fidius” are often added to his name, as seen in the inscription from the Tiber Island. The precise etymology and meaning of these titles is a matter of debate. “Dius” seems like it should be connected to “divus – godlike”, and “fidius” to the verb “fido – to trust.” The Romans also had an exclamation “medius fidius” which was much like “Mehercule – my god!” His name is also prefixed with another, Semo, which is also the object of much discussion and debate.

There was a shrine dedicated to him on the Quirinal Hill in Rome, located near a gate called of the ancient Servian walls called the Porta Sanqualis, which seems to take its name from him. Oaths sworn by Semo Sancus were always taken under the open sky, and ancient writers mention as a noteworthy fact that the shrine had no roof. Likewise, if such an oath were sworn in private house, it was done in that part of the atrium that was open to the sky to catch the rain, known as the compluvium. This shrine was also supposed to contain some very ancient objects, including some personal items that had belong to Tanaquil, the wife of Tarquinius Priscus, the fifth king of Rome. The remains of the shrine were uncovered in the 16th century, but later demolished.

(A drawing of a statue of Semo Sancus found on the Tiber Island in 1574, and now in the Lapidary Gallery of the Vatican Museums. Public domain image from Wikimedia Commons.)

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