The Barberini Mithraeum’s colours shine anew

ROME — The Cave of the Nymphs, written by the Neoplatonist philosopher Porphyry towards the end of the third century AD, is an highly unusual text for two reasons. First, it is the only complete example of an allegorical commentary on Homer to have survived intact from antiquity. Allegorical interpretation, a method of exegesis widely practiced since the Hellenistic period, rested on the following premise: certain poets, Homer in particular, deliberately concealed esoteric teachings about the sensible and intelligible realms within their verses, so that only readers initiated into the mysteries of wisdom could gain access to them. A further advantage of allegory was that uninitiated readers, lacking the critical tools needed to grasp a text's deeper meaning, would not risk misunderstanding delicate philosophical questions. They would simply be content with the surface of the text, its so-called literal meaning. The Cave of the Nymphs In The Cave of the Nymphs, Porphyry offers an allegorical interpretation of ten lines from Book 13 of the Odyssey, describing the moment when the sleeping Odysseus finally arrives in Ithaca and is left by the Phaeacians beside a cave inhabited by nymphs. From the detailed description of the cave, Porphyry draws out profound metaphysical questions, encoded in accordance with his Neoplatonic worldview — a syncretic blend of Pythagoreanism, Orphism, Egyptian beliefs and much else besides. This brings us to the second remarkable feature of the text: one of the religious traditions Porphyry adds to his interpretative mixture is Mithraism. From Syria to Spain The cult of the god Mithras, Sol Invictus, the Unconquered Sun, had Persian origins. Yet in late antiquity it spread far beyond the borders of present-day Iran, thanks to Roman soldiers who embraced it enthusiastically and carried it throughout the empire. Mithraea, the sanctuaries of the Mithraic cult, sprang up from Syria to Spain. They were underground spaces, usually quite small, where followers initiated into the different grades of the mysteries — seven in all — would gather. By the third century, Mithraism had become one of the most widespread cults in the Roman Empire. Christianity was also growing in popularity, and Porphyry, a vehement opponent of Christianity, appears to have regarded Mithraism as a considerably more civilised religious alternative — one more closely aligned with the philosophical foundations of paganism. A mystery religion The Cave of the Nymphs is full of references to Mithraism and connections between the cult, Platonism and Pythagoreanism. Because Mithraism was a mystery religion, and therefore secretive, Porphyry's text is a treasure: a written record of a forgotten cult. Our most important source of information about Mithraism, however, has always been its imagery. And one of the most striking surviving examples is the fresco in the Barberini Mithraeum, which reopened to the public on 3 October after a lengthy period of restoration work. A Mithraeum unlike any other Discovered in 1936 during construction work on the Savorgnan di Brazzà building, the Barberini Mithraeum is unique in the world for its exceptionally well-preserved late-antique fresco. The depiction of Mithras slaying the bull dominates the chamber, which is almost 12 metres long and just over six metres wide. Its vivid colours and exquisite details — such as the tiny stars lining the inside of the god's cloak — are extraordinary. Traces of colour also survive on one of the walls and along sections of the raised side benches, known as praesepia, where participants sat during the rituals. Although many statues depicting Mithras killing the bull have survived, frescoes are exceptionally rare. In Rome, the only other example is at Santa Prisca, on the Aventine Hill. Closed to the public, it contains fragments of a painted statue and only faint traces of colour. The bull-slaying scene The killing of the bull, the high point of Mithraic worship, was a rare event that could not take place in every mithraeum, given the limited size of these sanctuaries. The only Roman mithraeum equipped with a fossa sanguinis, or blood pit, and enough space for the great sacrifice is the one beneath the Baths of Caracalla. Some of the earliest scholars of Mithraism believed that the tauroctony, or bull-slaying scene, celebrated an ancient Persian myth about the origins of the universe: the bull's blood waters the earth, bringing life into being. More recent studies, however, have suggested that the scene represents a star map, the product of a syncretic fusion of Persian religion, Stoic philosophy and Greek cosmology. The creator of the universe According to this interpretation, Mithras, at the centre of the fresco, would represent the Demiurge, the creator of the universe. On either side of him, the torchbearers (dadophori), Cautes and Cautopates, would symbolize the rising and setting sun, while the signs of the zodiac above them would represent the planets. Mithraism reached the height of its popularity in the third century, as the sheer number of mithraea dating from that period demonstrates. In Tarsus, archaeologists have even discovered coins from the reign of Gordian III bearing the image of Mithras slaying the bull. The fierce attacks on Mithraism in the writings of Church Fathers such as Justin Martyr, Tertullian and Firmicus Maternus reveal just how great a threat the emerging Christian faith considered the cult to be. The colours of the soldiers' god Indeed, sometime between AD 354 and 360, the Church began celebrating the birth of Christ on 25 December — the same date on which the birth of Mithras was celebrated — rather than 6 January. Was this an attempt to eradicate the cult of the Persian god? It is not impossible. Moreover, the harsh anti-pagan laws enacted by Theodosius I in the last quarter of the fourth century, the subsequent destruction of the mithraea and the almost complete disappearance of the cult by the end of that century demonstrate just how relentless the Christian repression was. And yet, the bowels of Rome, which still hold so many surprises, have preserved the colours of the soldiers' god intact — the god whose cyclical sacrifice brings the universe into being. This article was reviewed by an external translation partner