I've often thought about, talked about and written about something that happens very easily when you sit with a very young child and read them a book.
As you read, a child with sight and hearing will hear the words you're reading and look at the pictures. These are never the 'same' story. Pictures don't really 'illustrate' the words. They tell a story or stories that are related in many different ways to the words that the child is hearing. But the child will be reading or trying to read the pictures while hearing and trying to interpret the words.
This means that complicated triangles and lines are being set up between interpreting words, interpreting pictures, interpreting how words are relating to pictures, how pictures are relating to words.
And it's never static.
What you get on one page, is different from what you get on another. What you get on one double page 'spread' is different from what you get on the next. And, if it's a story - fiction or non-fiction, there are all sorts of links and references and 'ties' between the page you're looking at and what precedes it. If you read the book more than once, the links and references stretch forwards as well as backwards because you know what's coming next.
What's more, artists and designers, vary the pages, creating expectations and upsetting them with variations in rhythm of words, rhythm of pictures, where pictures are placed on the page, how many, what change in colours and so on. Characters, features, landscapes may appear or disappear, change once, several or many times with no explicit mention in the text.
All this has to be made coherent by the child. That's to say, the child, in 'getting' the book, getting to like it, understand it, enjoy it, has to find how these things relate in ways that the child can make sense of. This involves the rest of their lives. That's to say, it all has to link with the world and the language(s) they're encountering in everyday life. It will probably link into and hook up with other books, and other 'texts' from TV, film, videos and so on. The act of interpreting will be made by the child using his or her experience of all these things. Running to and for between the 'dead' (inanimate) pages of the book, memories of life and language, and comparing them to 'live' things around them. More interpretation and reflection.
Some children get to do a huge amount of this. Some children get to do very little.
There are important social and political reasons for this. Enormous effort goes into putting people off doing these things: libraries close, early years work in schools focusses more and more on 'decoding' and less and less on frequent reading and re-reading of books which enables this kind of 'work' (or 'pleasure') to happen, the multi-billion dollar front-running media of the day - TV, tablets and videos - say, 'Watch-me!', 24 hours a day, and though I'm not one to say that this is all crap or meaningless or bad, some of this complex interaction that I'm describing that takes place with book-sharing is less prominent, less necessary.
People wonder how it is exactly that some children arrive in school aged 4 or 5 and seem 'school-ready'. One way to look at this is in a very reductive way, and see it in terms of being able to hold a knife and fork and do phonics. There's another way of looking at it in terms of being able to access school-knowledge and higher, more abstract ways of thinking - whether that's in maths, science, humanities or back with literature and language.
Sharing picture books may seem like a far cry from the abstract thinking needed to understand these subjects. What I'm suggesting is that in fact, it isn't. In order to do the 'work' (pleasure) of interpreting sound and image of the picture book in the circumstances I've described, a child has to use and develop a range of interpretation and reflection strategies. These are powerful capabilities, (call them 'transferrable skills', if you like) that you can use and develop through the rest of your life, long after you think you've put them behind you.
All this is extremely hard to explain to people in charge of education. And even harder to convince them of the need for it.