Archaeologists said the stones were of "exceptional quality". The experts from East Lothian Council, Historic Scotland and AOC Archaeology Group have been examining and carefully removing the stones for the past year. Only the backs and sides were visible until this month, when it was finally safe to make a full inspection.
The first stone has side panels showing a lyre and griffon as well as pictures of a jug and bowl… objects that would have been used for pouring offerings on the altar. The front face bears a carved inscription dedicating the altar to the god Mithras. This is the furthest north that such dedications have been discovered.
Mithraism was a mystery religion, popular with the military in the Roman Empire from the 1st to 4th Centuries. In antiquity, texts refer to "the mysteries of Mithras", and to its adherents, as "the mysteries of the Persians." Some scholars postulate that the Mithraic Mysteries were founded by Zoroaster, that Mithraism was the Roman form of Zoroastrianism (Mazdaism), disseminated from the East. The god Mithra came to Rome accompanied by a large representation of the Mazdean Pantheon. But there is great dispute about whether there is really any link with Persia, and its origins are quite obscure.
The Greek biographer Plutarch (46 - 127) says that the pirates of Cilicia, the coastal province in the southeast of Anatolia (Asia Minor), were the origin of the Mithraic rituals that were being practiced in Rome in his day: "They likewise offered strange sacrifices; those of Olympus I mean; and they celebrated certain secret mysteries, among which those of Mithras continue to this day, being originally instituted by them." The 4th century commentary on Vergil by Servius says that Pompey (Gnaeus Pompeius Magnus) settled some of these pirates in Calabria in southern Italy. But whether any of this relates to the origins of the mysteries is unclear.
Adepts of the Mithraic Mysteries had a complex system of seven grades of initiation, with included ritual feasting. They met in subterraineian temples, which survive to this day in large numbers. The seven grades of initiation into the mysteries of Mithras, which are listed by St. Jerome, were connected to the planets. A mosaic in the Ostia Mithraeum of Felicissimus depicts these grades, with heraldic emblems that are connected either to the grades or are just symbols of the planets. The grades also have an inscription besides them commending each grade into the protection of the different planetary gods... Saturn, Sol, Luna, Jupiter, Mars, Venus & Mercury.
The front face of the second stone shows female heads, which represent the four seasons. All are wearing headdresses, spring flowers, summer foliage, autumn grapes and a shawl for winter. The centre of the stone contains a carving of the face of a God, probably Sol (Sol Invictus), wearing a solar crown. The eyes, mouth and solar rays are all pierced and the hollowed rear shaft would probably have held a lantern or candle letting the light shine through, similar to a Halloween pumpkin or turnip lantern.
An inscription on a panel beneath the four seasons is currently partially obscured, but experts said it was likely to bear the name of the dedicator - who is believed to be a Roman centurion - and the God to whom the altar is dedicated. Traces of red and white paint are still visible beneath the inscription panel, which experts said suggested it was originally brightly painted.
Ruth Currie, East Lothian Council's cabinet member for community wellbeing, said: "This is enormously exciting and its significance could be huge… "These beautiful artifacts could reveal a whole new strand of East Lothian's history and possibly even shed light on the way the Romans lived on an international scale."
Dr Fraser Hunter, Iron Age and Roman curator at National Museums Scotland, said: "The quality of these sculptures is remarkable, and they will tell us an enormous amount. This is the first evidence for the god Mithras in Scotland, and changes our view of Roman religion on the northern frontier." Dr James Bruhn of Historic Scotland said: "The discovery of altar stones to the eastern God Mithras adds a fascinating new chapter to the story of Inveresk's Roman past."