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The halo has stuck in Christian art ever since, although it has undergone some adaptation over the years. It was a signal of Christianity's metamorphosis from a marginalised religion to an official power structure in the west. This new arrival in Christian iconography occurred from around the 300s AD, more than two centuries after it had appeared in Buddhism. Then, with the growing acceptance of Christianity in the Roman Empire, artists began to represent Jesus with a halo, now regarded as the highest symbol of divinely sanctioned authority. Constantine (Emperor 306-337CE) recognised the iconographical power of the halo, so he and his successors arrogantly appropriated it and used it in artistic representations of themselves. Both gods combined graceful masculine physiques with divine powers, linked to the sun's radiance and authority, and so were worshipped by the most powerful members of society, especially the Roman Emperors. Mithras later influenced the iconography of another Roman deity – Sol Invictus (the "sun unconquered").
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Meanwhile Mithra was also winning the hearts of the invading Roman Empire to the west – to the extent that Mithraism evolved into a major Roman religion. So much so that the iconography of Buddha – even from the earliest visual representations of him, such as the Bimaran reliquary (which might date from the late First Century AD), show him with a Mithraic halo. This youthful and attractive god with his divine radiance had an obvious appeal to a growing number of people around the Hindu Kush. Both empires, which were steeped in ancient Iranian cultural history, brought coinage with them that represented Mithra with a halo.
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In the First Century AD, the Indo-Scythians (nomads from Iran) and the Kushans (from Bactria, Afghanistan) invaded the regions to their southeast, the territories now covered by modern-day Pakistan, Afghanistan and northern India. So how did the halo's influence spread across the world and between religions? The initial movement of this piece of religious iconography is outwards east and west from its birthplace in Iran, in the hands of some of the past's most powerful empires. It has been contested that the concept of divine glory (known as 'Khvarenah') in Zoroastrianism is intimately connected with the radiance of the sun, and that the halo was the pictorial means of relating this quality to Mithra, just as it had been for Ra. It seems to have been conceived as a distinguishing feature of Mithra, deity of light in the Zoroastrian religion. The earliest examples of a disc halo come from the 300s BC in the religious art of ancient Iran. But the distinctive circular disc halo is an invention of a later date and presumably the result of unique religious ideas. Likewise in the art of ancient Greece there are occasional representations of rayed crowns of light surrounding the heads of mythological heroes to suggest their unique divine powers. However, these are inscribed around the whole bodies of holy figures, rather than just their heads. Meanwhile, some artefacts from the city of Mohenjo-daro (in the Indus valley), created in the 2000s BC, feature what look like rayed auras. In ancient Egypt, the solar deity Ra was commonly shown with a circular disc representing the sun – although this was above his head rather than behind it. It is likely to have evolved from very early art traditions.
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It had not featured in any prior religion, and yet it became a fixed piece of religious iconography across Eurasia within a few centuries. Investigating the function of the original circular halo in religious art only takes us back as far as the 1st Century BC. One amusing proposal was that it derived from protective plates fixed to statues of gods to protect their heads from bird droppings. Perhaps it was a simple decorative embellishment. Alternatively, it may have been a symbol of a divine aura emanating from the mind of a deity. Why was this symbol invented? It has been conjectured that it could have originally been a type of crown motif. There are many variants, including rayed haloes (like that on the Statue of Liberty) and flaming haloes (which feature in some Islamic Ottoman, Mughal and Persian art), but the most distinctive and ubiquitous is the circular disc halo. This aura around a holy figure's head expresses their glory or divinity and can be seen in art across the world. The ancient symbol that spanned millennia But if you just look at them, you will see a symbol that connects them all – the halo. Christianity, Buddhism, Hinduism, Zoroastrianism and Greek mythology are usually regarded as utterly distinct religions, largely defined by their differences.
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