C. S. Lewis thought about myth and cosmologies in more ways than one

Excerpts about myth (as light from another, more real world) from Surprised by Joy

We are taught in the Prayer Book to "give thanks to God for his Great glory," as if we owed Him more thans for being what He necessarily is than for any particular benefit He confers upon us; and so indeed we do and to know God is to know this. But I had been far from any such experience; I came far nearer to feeling this about the Norse gods whom I disbelieved in than I had ever done about the true God while I believed. Sometimes I can almost think that I was sent bact to the false gods there to acquire some capacity for worship against the day when the true God should recall me to Himself. (77)

The real clue [that helped Lewis move from Theism to Christianity and helped him distinguish among the multiplicity of religions] had been put into my hand by that hard-boiled Atheist when he said, "Rum thing, all that about the Dying God. Seems to have really happened once"; by him and by Barfield's encouragement to a more respectful, if not more delighted, attitude to Pagan myth. (235)

I was by now too experienced in literary criticism to regard the Gospels as myths. They had not the mythical taste. And yet the very matter which they set down in their artless, historical fashion . . . was precisely the matter of the great myths. If ever a myth had become fact, had been incarnated, it would be just like this. Myths were like it in one way. Histories were like it in another. But nothing was simply like it. (236)

. . . yet also numinous, lit by a light from beyond the world, a god. But if a god--we are no longer polytheists--then not a god, but God. Here and here only in all time the myth must have become fact; the Word, flesh; God, Man (236).

Excerpts for "Myth Became Fact" in God in the Dock (mythic reality enters history in Christ)

You are not looking for an absrtact 'meaning' at all. If that was what you were doing the myth would be for you no true myth but mere allegory. Your were not knowing, but tasting; but what you were tasting turns out to be a universal principle. The moment we state this principle, we are admittedly back in the world of abstraction. (66)

What flows into you from myth is not truth but reality (truth is always about something, but reality is that about which truth is ) (66).

The heart of Christianity is a myth which is also a fact. The old myth of the Dying God, without ceasing to be myth, comes down from the heaven of lengend and imagination to the earth of history. It happens--at a particular date, in a particular place, followed by definable historical consequences. We pass from a Balder or an Osiris, dying nobody knows when or where, to a historical Person cruicfied (it is all in order) under Pontius Pilate. By becoming fact it does not cease to be myth: that is the miracle. (66-67)

To be truly Christian we must both assent to the historical fact and also receive the myth (fact though it has become) with the same imaginative embrace which we accord to all myths (67)

Excerpts about cosmologies and "Models" (as backcloths for art) from The Discarded Image

In every period the Model of the Universe which is accepted by the great thinkers helps to provide what we may call a backcloth for the arts (14).

The medieval backcloth contains the order and influences of the planets, but not much about epicycles and eccentrics. Nor does the backcloth always respond quickly to great changes in the scientific and philosophical level (14).

The mass media . . . have in our time created a popular scientism, a caricature of the true sciences . . . (17).

Every Model is a construct of answered questions (18).

The Pagan elements embedded in it [the Medieval Model] involved a conception of God, and of man's place in the universe, which, if not in logical contradiction to Christianity, were subtly out of harmony with it (19)

Excerpts about myth (as a literary form) from An Experiment in Criticism, Chapter V (On Myth)

The stories I am thinking of always have a very simple narrative shape--a satifactory and inevitable shape, like a good vase or a tulip.

It is difficult to give such stories any name except myths . . . (Page 42)

. . . A myth means, in this book, a story which has the following characteristics.

1. It is, in the sense I have already indicated, extra-literary. Those who have got at the same myth through Natalis Comes, Lempriere, Kingsley, Hawthorne, Robert Graves, or Roger Green, have a mythical experience in common; and it is important . . . .
2. The pleasure of myth depends hardly at all on such usual narrative attractions as suspense or surprise. Even at a first hearing it is felt to be inevitable. And the first hearing is chiefly valuable in introducing us to a permanent object of contemplation--more like a thing than a narration--which works upon us by its peculiar flavour or quality, rather as a smell or a chord does. Sometimes, even from the first, there is hardly any narrative element. The idea that the gods, and all good men, live under the shadow of Ragnarok is hardly a story. The Hesperides, with their apple-tree and dragon, are already a potent myth, without bringing in Heakles to steal the apples.
3. Human sympathy is at a minimum. We do not project ourselves at all strongly into the characters. They are like shapes moving in another world. We feel indeed that the pattern of their movements has a profound relevance to our own life, but we do not imaginatively transport ourselves into theirs. The story of Orpheus makes us sad; but we are sorry for all men rather than vividly sympathetic with him, as we are, say, with Chaucrer's Troilus.
4. Myth is always, in one sense of the word, 'fantastic'. It deals with impossibles and preternaturals.
5. The experience may be sad or joyful but it is always grave. Comic myth (in my sense of myth) is impossible.
6. The experience is not only grave but awe-inspiring. We feel it to be numinous. It is as if something of great moment had been communicated to us. . . . (Pages 43-44)

. . . when I talk of myths I mean myths as we experience them: that is, myths contemplated but not believed, dissociated from ritual, held up before the fully waking imagination of a logical mind. (Page 45)

Since I define myths by their effect on us, it is plain that for me the same story may be a myth to one man and not to another. (Page 45)

The value of myth is not a specifically literary value, nor the appreciation of myth a specifically literary experience. He [the reader] does not approach the words with the expectation or belief that they are good reading matter; they are merely information. Their literary merits or faults do not count . . . (Page 46)

As I have already said, the degree to which any story is a myth depends very largely on the person who hears or reads it. An important corollary follows. We must never assume that we know exactly what is happening when anyone else reads a book. For beyond all doubt the same book can be merely an exciting 'yarn' to one and convey a myth, or something like a myth, to another. (Page 48)

Here's more:

http://thefellowshipoftheking.net/2015/12/03/the-catholic-and-the-convert-a-brief-exploration-and-comparison-of-the-spiritual-influences-behind-jrr-tolkiens-middle-earth-and-cs-lewiss-narnia/

Myth as Truth (original is probably buried somewhere in the website linked above this).