“One of the texts I sometimes quote -- it's not a text, it's just a pronouncement -- was made by Pope Gregory the Great in about 592, I think. This was in connection with the question of whether it was okay to paint pictures on the wall of churches, given the commandment that forbids us to make representations of things. What he said was, "What words are to the reader, pictures are to those who cannot read." Which, on the face of it, seems to make sense. It seems sound, good policy. If you can read, you have the words; if you can't read, you have the pictures.
But what it does actually is make two assumptions that I think have bedeviled our understanding of pictures for a long time since then. One is that words and pictures are equivalent, whereas they are not. When you see an actor in a role on a screen, for example, that actor's face is forever afterwards associated with that character. It is very hard to disentangle the two. When we read about that character in a book, we can supply what the person looks like, and we supply all sorts of other things that are not there, because they don't have to be there. Words and pictures are not the same.
Another interesting difference between them is that words work in time, and pictures work in space. Pictures are very good at showing you where things are, what things look like, how far away things are -- that sort of thing. But a single picture on its own cannot show us the order of things happening. Stories are all about the order of things happening. This happened, and then that happened because of what happened earlier on. To do that, you need words, which are extremely good at depicting this because of the way verbs have tenses, and the way sentences have grammatical sequence of clauses and so on, all of which help us to understand the order of things. So words and pictures aren't equivalent. That's the first kind of mistake that Pope Gregory made about them.
The second consequence of what he said is that it set up a sort of hierarchy of esteem in which educated people have the words, but people who are not educated -- children, illiterate people, slaves -- have to make to do with pictures. This has curious consequences in the way, for example, that now children's books are expected to be illustrated and adult books are not expected to be illustrated, that, when children reach a certain age, we say, "Come on, stop reading comics now; read proper books." And the fact that we just don't think visual literacy is important enough to teach in school.”