The following is an excerpt from a "Road To Emmaus" interview with the well-known French Iconographer, Emilie Van Taack. She was a faithful student of Leonid Ouspensky. (Taken from The Iconographer's Handbook, one of the sites belonging to Anna Tregubov DuMolin, a wonderful iconographer from New Hampshire. Click here to see her site.)
(Image of Ouspensky painting on his famous stool. All his icons were painted there.)
On Canonical Rules:
"...There is only one rule, Rule 82, decreed by the Council in Trulo, part of the Sixth Ecumenical Council. This is the iconographic canon, in which it is stated that icon painter must follow older painter, that they must be in this stream of tradition, but exactly how they are to do this is not described. What is stated is that an icon must show both the humility of the Man Jesus and His glory as God; that is, it must manifest the Incarnation. In an icon of the Lord, you must be able to see that this man who is preseneted is not only man, but also God. You must see the Person of Christ. The Council made this rule because at this period there were still some symbolic representations, like in the early Church, representing Christ by a fish, or as a sheperd, or as a lamb - not the hypostatic representation of the Person of Jesus Christ. The Council said that all of these symbolic representations are like the shadows of the Old Testament. Since we have been illumined by the truth of the New Testament, we no longer use these old and outdated symbols, but we must present Christ Himself. Who incarnated into a human body and can be represented in the body. This is the only canon, the only rule of the Church.
In defining what is "canonical" in icon painting, we have, of course, many beautiful old canonical icons to refer to. But canonicity is difficult to define. I cannot tell you what is canonical, because icons themselves define the canons. It is a circle, and we must accept it like this. By looking at these beautiful icons, studying them, copying them, little by little they help you to see yourself this image of Christ, and then you will be able to paint it without looking to the old, because you will have it in your own heart. This is a saving situation, because in this way we cannot possess the canon: it is a free gift that God gives or takes back as He wills."