Think of Byzantium, and a color leaps to mind. That color is gold.

The empire ruled from the crossroads of the Mediterranean and the Black Sea for a thousand years between AD 324 and its final collapse in 1453. At the Getty Villa in Pacific Palisades, where a rare and stunning exhibition of Byzantine art recently opened, gold is everywhere.

It's the ground on which biblical scenes unfold, from the tender nativity of Jesus to the brutal Passions and miraculous resurrection of Christ. It's in the air breathed by saints speaking to the faithful from painted manuscript pages.

It's in the threads woven into tapestry cloths used in liturgical rituals on church altars, and it colors the mosaic tiles built into floors and walls of buildings. And of course it's the substance of delicate jewelry and lavish body ornaments — of golden rings, arm cuffs, necklaces and earrings.

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Gold is even suggested in simpler, more humble but no less beautiful objects such as glazed clay dishes and bowls. The linear images of birds, dancers or lions are made from incising into the pots' red clay, but the shimmering slip-glaze that surrounds the figures is mostly in varying shades of yellow. Sometimes the glaze is even subtly iridescent.

Why gold? On the evidence, because of its capacity to serve two rulers: The exhibition is titled "Heaven and Earth: Art of Byzantium from Greek Collections," and its 187 objects together demonstrate how gold can represent power that is both earthly and heavenly at once.

The Byzantine Empire is fundamentally noteworthy because it was the first in which the secular power of the state fused with the religious authority of Christianity. In the West, not until the U.S. Constitution came along, were the two finally uncoupled.

When Emperor Constantine moved the capital of the Roman Empire east to the Bosporus Strait joining Europe and Asia, he left behind the tangled mythologies of Greco-Roman religion. Back in Rome, mere mortals had been practically a breed apart from the dozens of indifferent deities romping all around them. But Christian monotheism, which Constantine embraced, changed all that.

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Spirituality, the search for the sacred in humanity, was in its way a whole new concept. Gold emerged as a bridge. Its everyday value as currency was intrinsic. But it also possessed distinctive visual properties. Rome's old material practicality was linked to new spiritual abstractions.

Gold is all hard surface with no spatial depth. Yet when used in a painting or mosaic, it shatters the rational articulation of space.

The mosaic body and clothing of the apostle Andrew in a magnificent, late-11th or early-12th century wall decoration is an elegant network of outlines. The life-size striding figure's marvelous animation is driven by linear whorls at his bodily joints. Almost like origami, the weightless, paper-thin figure traverses a shimmering golden field.

Gold's light-reflective qualities, especially in direct sunlight or in darkened rooms illuminated by candles or oil lamps, can create spectral illusions of infinity. You seem to be able to touch the ineffable with your hand.

To represent the dual nature being claimed for Christ — both man and god, the earthly and the divine — what could be more useful?

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The second of the show's three galleries is the most powerful. A dozen or so gilded icons, together with several mosaics, manuscript illuminations and a fragment of a wall fresco, come from different centuries and various parts of the far-flung Byzantine Empire, which encompassed much of the Mediterranean region. (The show is installed thematically, not chronologically or geographically.) But they all embrace a linear style of rendering, flat and two-dimensional, that downplays naturalism in favor of abstraction.

The face of the dead Christ, his head sunken into his shoulders, in an icon of "The Man of Sorrows," is surrounded by rivulets of hair and beard drawn as meandering, rhythmic patterns. An orb adorned with symbols for Christ as Eternal Judge represents the heavens, nestling in the left hand of Archangel Michael, but it is less a dynamic sphere than a swirling disk. Both Christ and the angel are low relief forms set in gilded realms rather than worldly figures full of flesh and blood.

Christ is laid out on a tomb slab on an exquisite, 6-foot-long woven liturgical cloth, one of the great treasures made near the empire's end. He is flanked with Communion representations of the body and the blood. The ensemble creates an elaborate, two-dimensional drawing in glittering embroidery thread.

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