My understanding of this principle is not sophisticated (and so may by flawed or incomplete) but nevertheless here it is: that in order emphasize the point that there is an invisible reality beyond what is seen of a particular object, some of the visible elements are veiled in order to emphasize, and so to reveal to us, this inner, or invisible, reality. This is true for all veiling - human veils, humeral veils, chalice veils and so on. How does this work?
First veiling is not hiding. When veiled the form beneath may not be visible directly, but it is still perceptible albeit in a less distinct form. We know what is veiled. For example, the form of a person is still discernible when clothes are worn. The form of the chalice is still recognizable even when veiled, as much by how it is handled as by the outer modified form. It relies on our knowledge of what is beneath it. If we did not know what a woman is, or a chalice is, we would not have a sense of a chalice veiled, but rather of an object in which the fabric we see represents the surface of it and is intrinsic to it.
When we recognize a veiled object, it makes the point that there is an inner reality that is not directly visible. So the veil is visible, but beyond it is the chalice, perceptible but invisible. In grasping this reality, it makes the point to us that the object itself, even when unveiled, has essential elements that are both visible and invisible. When unveiled, we can be so absorbed with the visible elements that perhaps we fail to grasp fully the invisible realities. So the partial hiding of the visible elements allows us to focus on the invisible.
In order for this to have any force at all, there must be invisible realities present in the object veiled. The human person is both body and soul; the body is visible, the soul is not. The chalice contains the wine in which after consecration Christ will be truly present, despite outward appearances.
Now to icons: if we apply the same argument, in order for the cladding on an icon to play the part of veiling, the icon must contain essential elements that are invisible and worthy of veneration. In point of fact the icon does not. Therefore, the cladding does not play the part of a veil.
Icon is an image worthy of veneration only to the degree that it is visible. The relationship to the person depicted is set up through the imagination of the viewer and by virtue of what is seen. In this sense the cladding becomes the icon and that part that is hidden ceases to be so. In this we follow the theology of Theodore the Studite, the Eastern Father who settled the iconoclastic controversy in the 9th century. “Theodore quotes a custom already mentioned by Leontius of Neapolis and by Patriarch Germanus: once an icon is worn and has lost its imprint’ (charakter), it will without hesitation be thrown into the fire “like any useless piece of wood’. If the icon as such were a grace-filled object, nobody would dare burn it. It would in itself be some kind of sacred relic. Different from John Damascene, who positions icons and relics on the same level, Theodore the Studite sees the sacredness of the icon entirely in its character, its portraying depiction.’” (p. 226, Christophe Schonborn, God’s Human Face, Ignatius Press)
