Tolkien On Imagination

From the Notion Club Papers, which is included in Sauron Defeated. I thought it rather interesting.

‘When you are writing a story, for instance, you can (if you’re a vivid visualizer, as I am, and are clearly visualizing the scene) see two places at once. You can see (say) a field with a tree and sheep sheltering from the sun under it, and be looking round your room. You are really seeing both scenes, because you can recollect details later. … As far as my own visualizing goes, I’ve always been impressed by how often it seems independent of my own will or planning mind (at the moment). Often there is no trace of composing a scene or building it up. It comes before the mind’s eye, as we say, in a way that is very similar to opening closed eyes on a complete waking view. I found it difficult, usually quite impossible, to alter these pictures myself, that is my purpose. As a rule I find it better, and in the end more right, to alter the story I’m trying to tell to suit the pictures. If the two really belong together – they don’t always, of course. But in any case, on such occasions you are really seeing double, or simultaneously.’

C. S. Lewis mentioned something like this, too, I think, when talking about how he came to write Narnia. He had ‘pictures’ of such things such as a faun standing in the snow with an umbrella. I wonder if the pictures they talk about predate the stories they wrote, or as they wrote the stories or thought them out, the pictures cropped up. Hm.
If these pictures are such as I suppose them to be, then I know of one instance where I had to alter my story to fit the ‘picture’ that I have of a scene. Not very interesting to others, perhaps, but my hero was meant to be walking through a valley that came out onto a plain, but instead I saw him standing on top of a cliff looking out over that same plain. And the mountains that I’d put in my map were in different places in the picture. Darn.
But they do seem to come prefabricated, to a certain degree, which helps in describing detail. Anyhow, I, as I said, thought it was an interesting quote.