In the Roman Empire, alongside the public cults of the city, celebrated for the good of the community, there flourished religions that people joined by personal choice through initiation. Scholars call them "mystery cults". Two of them, that of the Egyptian goddess Isis and that of the god Mithras, spread remarkably widely and have left us archaeological and literary evidence of great interest, including in Italy.
Isis, from the Nile valley to the Mediterranean
Isis was one of the great deities of Pharaonic Egypt, wife of Osiris and mother of Horus. Her myth tells of her search for her husband's dismembered body, its reassembly and the birth of the son who would avenge his father. In the Hellenistic period, under the Ptolemies, the cult opened up to the Greek world and spread through Mediterranean ports.
It reached Italy early, mainly through Campania and trade with Delos and Alexandria. Its relationship with Rome was initially fraught: in the Republican period Isiac shrines on the Capitol were demolished several times by decision of the Senate. Under the Empire the cult took hold, and Rome gained the great Iseum Campense in the Campus Martius.
The Iseum of Pompeii
The most vivid evidence is in Pompeii. The Temple of Isis, rebuilt after the earthquake of AD 62 and buried by the eruption of 79, was uncovered in the eighteenth century and deeply impressed Grand Tour visitors. It features:
- a temple on a high podium in the middle of a colonnaded courtyard;
- a small building, known as the purgatorium, with an underground basin for lustral water, symbolically linked to the Nile;
- a hall for the meetings of the faithful and rooms for the priests.
The frescoes and furnishings, now largely in the National Archaeological Museum of Naples, show priests with shaven heads and scenes of worship.
The initiation of Lucius
The most important literary source is the eleventh book of the Metamorphoses by Apuleius, a second-century writer. The hero, Lucius, who has been turned into a donkey, regains human form thanks to Isis during a procession and decides to devote himself to the goddess.
Apuleius describes the stages of preparation: a period of waiting, abstinence from certain foods, purifying baths, instruction by the priest. About the rite itself, however, Lucius holds back: he says only that he approached the boundary of death, passed through all the elements and saw the sun shining at midnight. It is a perfect example of how initiatory secrecy was respected even in a text meant for the public.
The cult also had public festivals, such as the Navigium Isidis, the spring festival that opened the sailing season.
Mithras, the god of the cave
The cult of Mithras spread through the Empire from the late first century AD and flourished until the fourth. The god's name derives from an Indo-Iranian deity, but the Roman cult has features of its own, so much so that scholars debate how closely it is really linked to Persia, as Franz Cumont argued in the nineteenth century.
Worshippers met in the mithraeum, a room often underground or built to resemble a cave, with two side benches for the ritual meal. On the back wall stood the tauroctony: Mithras slaying a bull, accompanied by recurring figures such as a dog, a snake, a scorpion and two torch-bearers.
The seven grades
Initiates of Mithras, men only, advanced through seven grades, known from a letter of Jerome and from inscriptions and mosaics:
- Raven
- Nymphus, the "bridegroom"
- Soldier
- Lion
- Persian
- Sun-Runner
- Father
The Mithraeum of Felicissimus at Ostia preserves a floor mosaic with the symbols of each grade. In Italy the mithraeum of Santa Maria Capua Vetere, with its frescoes, and the one beneath the Basilica of San Clemente in Rome are also famous.
What they had in common
Different as they were, these cults shared certain features: voluntary membership, secret initiation, a community of brothers and sisters or of brothers only, the promise of a personal relationship with the deity. They did not exclude participation in traditional cults. Both disappeared with the anti-pagan laws of the late fourth century.
For Studio Esoterico Cornelio, the cults of Isis and Mithras show how initiation has always answered a precise need: to give communal and symbolic form to a personal spiritual search.
In short
- Isis and Mithras were among the most widespread mystery cults of the Roman Empire.
- The Pompeii Iseum and the eleventh book of Apuleius's Metamorphoses are the main sources on the Isiac cult.
- The Mithraic cult, reserved for men, took place in cave-like mithraea and had seven initiatory grades.
- Both vanished with the anti-pagan laws of the late fourth century.