Have you ever noticed that even though Orthodox icons are bathed in golden light, none of the figures represented ever has a shadow? Far from being an artistic choice, it is deeply rooted in Orthodox theology.
Its origins lie in the Transfiguration of Christ. This was the moment when the three apostles Peter, James, and John accompanied Christ to the top of a mountain to pray. There Christ began to shine with a bright light, before conversing with prophets and with God, in a display of his divinity.
Although the mountain is unnamed, it has often been identified as Mount Tabor since the time of Origen. It became a place of pilgrimage and is home to the Church of the Transfiguration. It has also inspired imitators, with the 15th century Hussite rebels of Bohemia founding a new city named Tabor in what is now Czechia; although there is no divine light there, the beer is very good.
Within Orthodox theology this divine light became known as the "Light of Tabor". The Athonite monk St. Gregory Palamas formulated the theological doctrine in response to accusations of heresy. He argued that a saint could attain such purity (a doctrine running dangerously close the monastic heresy of Messalanism) that they would also experience a manifestation of this divine light and cited the appearance of the Burning Bush to Moses as an earlier example.
This experience is called "theoria", although Palamas was clear that whilst divine energy could be experienced, divine essence could not. Just as Christ was the divine made flesh, so too every Christian could sense the divine pneuma (spirit) in the veils of materiality. Gold icons wreathed by incense in a dark church give the sense of matter trapped in a state of temporary lingering in the world; just like human beings. Without shadow the icon is bathed in a light which is unanimated. Matter becomes kecharitomene, where grace infuses the surface in order to bring the presence to light.
This divine light explains why icons are gold - and also why they have no shadows. Western European art is reliant on perspective but in an Orthodox icon the perspective is God's. There are no shadows because the light by which we 'see' in the icon is the "Light of Tabor" and this light leaves no shadow because of its divinity.
The icon is itself a window into heaven, which is why they are shown such reverence. If the Apostles fell to their knees when they say the "Light of Tabor" on the mountain, then so should we when we see that same light in an icon. This is why they can have light - without shadow.
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