"Everything began with images," [C S Lewis] wrote: "a faun carrying an umbrella, a queen on a sledge, a magnificent lion. At first there wasn't even anything Christian about them; that element pushed itself in of its own accord." There was not, he says over and over again, an evangelistic plan in the making of Narnia, no apologetic scheme: "Some people seem to think that I began by asking myself how I could say something about Christianity to children; then fixed on the fairy tale as an instrument; then collected information about child-psychology and decided what age-group I'd write for; then drew up a list of basic Christian truths and hammered out "allegories" to embody them. This is pure moonshine. I couldn't write in that way at all."
Or perhaps he could have, but knows that it would have been a dreadful mistake, a giving over of his imaginative life to the "expository demon." What he has to do instead is trust the images that come into his mind - or, more accurately, trust that he is being formed as a Christian in such a way that the images that come to his mind are authentic ones, ones that lie at, or at least near, the centre of his soul. He can do this only if he rejects not only the market-driven questions of modern authors and publishers ("What do children want?") but even the more morally sound question of the Christian apologist ("What do children need?"): "It is better not to ask the questions at all. Let the pictures tell you their own moral. For the moral inherent in them will rise from whatever spiritual roots you have succeeded in striking during the whole course of your life."
This is a terrifying, or liberating, word: liberating in that one need not expose oneself to the sanctimonious drudgery of drawing up lists of Christian truths and hammering out allegories that will meet the desires or needs of children. But terrifying because as those images rise from your mind you discover what you are really made of: you discover whether you are one whose moral and aesthetic responses have been shaped by the Christian narrative or whether you remain a person "without a chest," lacking in true spiritual formation. Trusting the images, you find out who you are.
From The Narnian, by Alan Jacobs, pages 243-4