It *proves* nothing.
Anyone simply looking at that image would not have a clue what it is about without someone telling them.
Any image that is going to be instructional, especially to uneducated masses, needs to be clear enough to be understood without being *interpreted* for them by someone else.
If the message is not intuitive, then it has not been presented well enough.
In that picture, there's absolutely no way that someone could intuitively know that that was *Gregory the Great* or what he was doing except some guy was writing something.
Like my first attempt at driving a car that had pictures for the controls instead of words.
Very nearly walked!
Happens to you often.