From a 1963 letter of Tokien’s (247 in the volume of letters) on the difficulties of putting the Silmarillion in publishable form.
I am doubtful myself about the undertaking. Part of the attraction of The L.R. [Lord of the Rings] is, I think, due to the glimpses of a large history in the background : an attraction like that of viewing far off an unvisited island, or seeing the towers of a distant city gleaming in a sunlit mist. To go there is to destroy the magic, unless new unattainable vistas are again revealed.
I found this passage in the introduction to The Book of Lost Tales, the first of twelve volumes in the History of Middle Earth – a set I’ve recently stumbled into owning. I’ve never thought myself enough a Tolkien fan to go outside the main lines but it occurs to me that when listening to the (Rob Inglis narrated) audiobooks last year I found myself most enjoying what I’ll unfashionably call the moral clarity and depth of the world. The action as action keeps its value and the world as world remains as convincing as ever but it’s somehow become Tolkien as thinker that is most intriguing. So I’m inclined to follow the cue of the divine book dispensary – which has never done me wrong – and (slowly) work through these volumes taking on faith the revelation of ‘new unattainable vistas’ of the specific sort I’m interested in.
