There is no other thing more frustrating to paint than the face of Jesus. To paint His face is hard well beyond the attainments of skill.
Skill for this task seems only necessary as antecedent exhaustion before the real strokes get made. In other words, more often than not, skill gets in the way. Artistic accomplishment alone is going to get you the most awful, rubber headache of a Jesus possible.
In light of that tortuous difficulty, one can understand the graphic shorthand that was developed over the centuries by iconographers. As my instructor says, you are making graphic annotations. You are not describing per se; you are realizing within the laws of the human hand.
What is it that we do when we come to terms with the limitations of something, like painting? We seek to attain what is most essential that can be attained through those limited means. Everything else gets bailed out. And in the end, depending on how well you've done, everything else has somehow been woven in.
If you do not recognize what you cannot attain through a limited medium, you will not attain to anything.
One can likewise understand the "shorthand" that was used to write Scripture - especially the New Testament. All that we know as Tradition was glanced at, in a kind of shorthand, like the graphic annotations of icons - like, yes, but also very different of course.
Take this passage from The Acts of the Apostles, Chapter 2:
Those who accepted his message were baptized, and about three thousand persons were added that day.
They devoted themselves to the teaching of the apostles and to the communal life, to the breaking of the bread and to the prayers.
Awe came upon everyone, and many wonders and signs were done through the apostles.
All who believed were together and had all things in common;
they would sell their property and possessions and divide them among all according to each one's need.
Every day they devoted themselves to meeting together in the temple area and to breaking bread in their homes. They ate their meals with exultation and sincerity of heart,
praising God and enjoying favour with all the people. And every day the Lord added to their number those who were being saved.
There is so much, so much condensed and yet not said in that little passage, and in particular: "They devoted themselves to the teaching of the apostles and to the communal life, to the breaking of the bread and to the prayers."
Already in those four things, which the one sentence mentions almost cursively, we get the sense that they are things that have a weight and world of their own, quite apart from the written word.
We can see by what Scripture does not tell us that Scripture is telling us something.
Scripture has a built-in modesty that tells us: do not take me up alone; that is heresy.
And where in scripture does it say that? Where indeed.
Perhaps sola scriptura doesn't nearly do as much disservice to Tradition as it does to Scripture. Iconoclasts after all, destroyed Scripture Illustrated.