In this chapter, Calpurnia, Valeria, and Gerius follow Cyrus to a Mithraeum, or a place where the god, Mithras, was worshiped. Mithras was an Indo-Iranian deity of friendship and order; he was worshiped as part of a mystery cult. He is nearly always depicted killing a bull, and his other symbols included a dog, a snake, and a scorpion. Since this was a mystery cult, members kept the activities and liturgy a secret, so we don’t know much about it. We know they participated in an initiation ceremony, and there were different levels of initiation into the cult. Only men were allowed to join. Scholars have found evidence for what Valeria sees, such as men wearing masks or costumes to represent levels of initiation, the cave-like structure of the Mithraeum, and the chant that the children hear. The little that we know about Mithraism comes from the remains of mithraic temples, dedicatory inscriptions, iconographic representations of the god, and other stone sculptures or wall paintings.
Although Mithras started out as a foreign deity, his worship became widespread in the Roman empire starting in the 1st century CE. The spread of the mystery cult was most likely caused by the exchange of ideas as the Roman army and merchants traveled more across the growing empire. Mithras was particularly popular amongst Roman soldiers. Interestingly, there was a Mithraeum built and dedicated in Ostia by a man named Felicissimus. Wouldn’t it be interesting if Calpurnia’s little brother grew up to build a Mithraeum?
At least sixteen Mithrea have been discovered in Ostia, and there were likely many more. In Ostia, there is a Mithraeum under a bath complex (similar to how the children follow Cyrus in the story), and it can still be visited today.
Immersive view of God Mithras statue in the act of killing bull to sacrifice it, the beautiful cave is located in the thermal’s mithraeum in archaeological excavations of Antica Ostia in Rome, Italy