“Two-Worlds in Old Russian Icon Painting” from Icons: Theology in Color by Eugene Trubetskoi.
In our icon painting this divine gold has a special name, assist, and is used in a special way. It never looks like solid gold; it resembles, rather, an ethereal, airy cobweb of fine rays emitted by God and lighting everything around. When it appears in an icon, God is always suggested as its source. However, in the presence of divine illumination assist often glorifies also the part of the environment that has already entered divine life and is seen as touching it very closely. For instance, it covers the throne and the brilliant mantle of Sophia the Divine Wisdom, and the mantle of the Virgin as she ascends to heaven. Angel wings and the tops of paradisial trees are often touched with it. In some icons, assist appears on the pointed domes of churches, never covering them but, rather, making them glitter with sparks and rays. The ethereal quality of these rays gives the domes an air of live, glowing, moving light. The garments of Christ in glory glitter with sparks; the throne and mantle of Sophia glow like fire; church domes burn to the sky. This sparkle and fire separate the otherwordly glory from the unglorious, the here-below. Our world merely aspires to the heights, imitates a flame, but becomes truly illumined by it only at the utmost heights that only the peaks of church life can attain. The trembling ethereal gold gives these peaks, too, a look of otherworldly brilliance.
In general the otherworldly colors were used with remarkable tact, especially by our Novgorod painters. Assist does not appear in the icons where Christ’s humanity is stressed, where he “took upon him the form of a servant.” But as soon as the artist sees Christ in glory, or wants to convey his imminent glorification, he introduces assist. Christ as an infant often glows with it when the artist needs to emphasize the eternal nature of the child. This fine gold covers the garments of Christ in icons of the Transfiguration, the Resurrection, and the Ascension. He shines with the same specific divine brilliance when he is shown leading human souls out of hell, or in paradise with the thief.
The strongest impact is achieved by the use of assist where the artist needs to contrast the two worlds, put a distance between the divine and the earthly. We can see this for instance, in the very old icons of the Dormition. One glance at the best of them makes it clear that the Virgin reclining on her deathbed, in her dark clothes, with all the familiars surrounding her, remains corporeally on this plane of being, the one we can touch and can see with our earthly eyes. But the figure of Christ in light raiment, standing behind the bed with the Virgin’s soul in the guise of an infant in his arms, is clearly an otherworldly vision. The whole figure shines and sparkles, separated from the intentionally heavy colors of the earthly plane by the ethereal weightlessness of its assist-covered lines...
Some icons…show in addition the Virgin already glorified, high in the sky, in that same golden brilliance, among angels also shining with assist.
Part 3: Blue