I just came across this recently in a letter of J.R.R. Tolkien to his son Christopher, dated January 1945 (for those of you who have the Carpenter collection of Tolkien's letters, it is letter 92, pages 109-110). In the letter he deals with the story of the Garden of Eden and brings up a point that I have stressed many times before regarding Genesis: that regardless of whether or not one believes in a literal Creation, it is troubling that Christians are somewhat embarrassed by the literal interpretation and automatically jump to an allegorical interpretation in the face of modern critiques of the Scriptures. Nevertheless, the story's value "as a story" points to its literal truth and is a concomitant of this truth. This letter is also very important in understanding Tolkien's idea on the meaning of "myth" as essentially truth in veiled language, versus the modern use of myth as something untrue.
As for Eden. I think most Christians have been rather bustled and hustled now for some generations by the self-styled scientists, and they've sort of tucked Genesis into a lumber-room of their mind as not veyr fashionable furniture, a bit ashamed to have it about the house, don't you know, when the bright clever young people called: I mean, of course, even the fideles who did not sell it secondhand or burn it as soon as modern taste began to sneer. In consequence they have forgotten the beauty of the matter even 'as a story.'
Lewis recently wrote a most interesting essay...showing of what great value the 'story-value' was, as mental nourishment. It was a defence of that kind of attitude which we tend to sneer at: the fainthearted that loses faith, but clings at least to the beauty of 'the story' as having some permanent value. His point was that they do still in that way get some nourishment and are not cut off wholly from the sap of life: for the beauty of the story while not necessarily a guarantee of its truth is a concomitant of it, and a fidelis is meant to draw nourishment from the beauty as well as the truth...
But partly as a development of my own thought on my lines of work (technical and literary), partly in contact with C.S.L., and in various ways not least the firm guiding hand of Alma Mater Ecclesia, I do not now feel either ashamed or dubious of the Eden 'myth'. It has not, of course, the same kind of historicity as the NT, which are virtually contemporary documents, while Genesis is separated by we do not know how many sad exiled generations from the Fall, but certainly there was an Eden on this very unhappy earth. We all long for it, and we are constantly glimpsing it: our whole nature at its best and least corrupted, its gentlest and most humane, is still soaked with a sense of 'exile'.