The later Roman Empire was a confusing period of political disunity, military overreach, and dramatic religious change. The Roman historian Cassius Dio’s damning verdict – that the Empire had declined from a ‘kingdom of gold to one of iron and rust’ (Epitome 71.36.4) – fairly sums up this era in both the scholarly and popular imagination. His view was echoed over a millennium later by the British historian Edward Gibbons, whose seminal work The Decline and Fall of the Roman Empire (1776-1779, London), which became the most widely cited work on the period, and has shaped the modern view. The trouble, the traditional narrative asserts, started following the glorious reign of Marcus Aurelius. His son and successor, Commodus, was a selfish and disinterested ruler; he left the running of the empire to a series of favourites, while his own behaviour became increasingly capricious and arbitrary. Commodus was assassinated, drowned by a professional wrestler in the public baths, and his death heralded the tumultuous Year of the Five Emperors (AD 193). Septimius Severus, the first African (and perhaps the first black) Emperor, briefly held the Empire together. His dynasty, however, was disastrous; it prefigured the Crisis of the Third Century. In one year (AD 238) there were no fewer than six Emperors. The Empire was divided in three – the Gallic Empire, Palmyrene Empire, and Roman Empire – with over twenty-six claimants to the imperial throne during the century. The crisis finished with the reign of Diocletian, who famously proclaimed the Empire too big to be ruled by one man, instead appointing a co-Emperor (Maximian) and two junior Emperors to rule alongside him. This new system only lasted one generation, before civil war set in again. It was shortly thereafter when Constantine I, the Great, inspired by a flaming cross in the sky at the Battle of the Milvian Bridge (AD 312), converted the Empire to Christianity.

This period of political decline was, by most assessments, marked by a similar decline in the arts. Artists rejected both the classicising models of Ancient Greece and the severe verism of Roman Republican and Early Imperial art. The serene, dignified expressions of past Emperors was replaced with an intense – in the case of Caracalla, almost insane (Metropolitan Museum of Art 40.11.1a) – expression, with wide eyes often looking upwards in a position of religious awe. For modern art scholars, any move away from Classical idealism is seen as a degradation of art, and so opinions of the Late Roman output are low. But, as this charming portrayal of a bull shows, there is much to appreciate in the newfound naivety of Roman art. The bull is depicted at rest, his legs folded under him. Significant effort has gone into accurately representing his posture, even though proportionally, his forelegs are far longer than his rear legs. Careful attention has also been paid to giving a sense of the musculature of the bull, with the dips and protrusions of the major muscle groups clearly rendered. He has an unusually long neck, with his head turned towards the viewer. Both his long neck and his facial features would perhaps look more appropriate on a horse; indeed, the figure even has a short mane which runs down the back of his neck. But in his short ears, wide eyes, and slight smile, we get a real sense of personality from him. The figure is carved from porphyry, a kind of granite in which feldspar crystals are held in a deep red or purple silicate-rich groundmass. Porphyry was considered the hardest rock known in antiquity.

Both due to its hardness and its colour (imperial purple, purpura), porphyry tended to be reserved for significant monuments. Immediately the quadruple portrait of the tetrarchs (the co-emperors Diocletian and Maximian, and their lieutenants Galerius and Constantius), now installed in a corner of St Mark’s Basilica in Venice, comes to mind. So we must wonder why a domestic-looking figure of a bull might have been composed in such a luxurious material. The symbolism of the bull in Roman art is most commonly associated with one figure: Mithras. The demigod Mithras was actually a borrowing from Zoroastrianism, the state religion of the Persian Empire, though the level of continuity between Persian and Roman Mithraism is currently debated. The central image of Mithraism, Rome’s most popular mystery cult, was the tauroctony, the scene of Mithras killing the bull. The exact meaning of this scene is unclear; in it, Mithras holds the bull by its nostrils with his left hand, and stabs it with his right. Other animals are present to help him: a scorpion pinches the bull’s testes, and a hunting dog goes for the bull’s neck. It is not impossible to imagine our bull as a participant in this scene. The bull is, after all, off-balance, and in a subdued position. It is not inconceivable that he was part of a wider statue group, showing the young Mithras subduing the animal. Mithraism was a rare survivor of the Roman polytheistic religion well into the Christian Age, helped by its status as a mystery cult, open only to the specially initiated. It was, however, seriously persecuted by the newly-Christianised Emperors, until it was eventually wiped out by the end of the Fourth Century AD.