It is well known that the Romans worshipped a whole range of gods and goddesses and tolerated other religions and belief systems so long as they did not interfere with the good order and running of their Empire. What is less well known is that they had little tolerance for 'secret societies' or 'mysteries' as they called them, taking the view that those societies were likely to be subversive. Many male Romans, particularly the military, on the other hand, were members of a mystery and one of the most mysterious was the Mitra mystery, popular between the 1st and 4th centuries AD.
I first came across this mystery in the museum at Cabra. A statue of Mithras was discovered in a Roman villa near the town. It was assumed that the villa was one location where members of this mystery met. The museum curators built a Mithraea, an underground vault in which the members met and practiced their rites.
Members were expected to graduate through seven grades of initiation, each grade being commended to a different planetary god. Novices joined as Corax, their deity being Mercury and progressed to Nymphus - Venus, Miles - Mars, Leo - Jupiter, Perses - Luna, Heliodromus - Sol and finally Pater - Saturn. Each grade had accompanying symbols that would be displayed on a gown. The promotion to each grade was witnessed by the other members and included an oath of secrecy and obedience and a catechism.
Not surprisingly, being so secret, there are not many of these catechisms around today, in fact only one is known and that was found on a fragment of papyrus in Egypt. It refers to the promotion to Leo grade and consists of a number of statements made by the Pater and responses by the initiate. Presumably the initiate had to make correct responses to pass the test. There is no record of what happened to him if he failed.
The god Mithras was probably 'borrowed' by the Romans from the Persians who worshipped Mithra. He was supposedly born from a rock as a youth, naked and carrying a knife or dagger in one hand and a torch in the other. His claim to fame is his single handed killing of a bull, an image that always appears in a Mithraea in the most prominent position above an altar. The image could be a relief in stone or, as at Cabra, a statue. This depiction is called the tauroctony. Mithras's second claim to fame is his banquet with Sol, both reclining on the hide of the slaughtered bull. I have a suspicion that this was the raison d'etre for the society.
Of the Mithraea discovered, many in Rome, others in Numidia, Dalmatia, Egypt and Britain, all appeared to have two long stone benches large enough for about 30 men. It is proposed that they were used by the members who lounged on them whilst they enjoyed a banquet. Food preparation rooms adjoined the vault. Mithraea by the way is a modern term, the Romans referred to their sacred cellars as speleum (from which our word spelaeology derives) or crypta.
Members of the cult recognised each other by a handshake. It all sounds very Masonic to me.