Of all of C. S. Lewis’s vast contribution to literature and to thought in the Twentieth Century, it is his last book, The Discarded Image, which is perhaps the most under-valued. Its treatment of the Mediaeval model of the universe, the way in which thinkers in the Middle Ages looked at the world around them, seems to be the province of scholars rather than of any general interest. But I think this is mistaken. The work contains valuable insight into the way in which Lewis himself thought as well as how our own thinking could benefit from a model of the world outside our ‘normal’ framework.
Lewis covers a lot of ground in what is really quite a short book. Part of the central hypothesis of the work, though, concerns the fundamental structure of the cosmos as viewed during the Mediaeval period. In brief, this consisted of a central Earth surrounded by a series of unfilled and transparent globes, each one larger and around the one within it. The first seven ‘spheres' or 'heavens', had fixed in them, like a jewel, one luminous body. Starting from Earth, the order was the Moon, Mercury, Venus, the Sun, Mars, Jupiter and Saturn ; the ' seven planets'. Beyond Saturn was the Stellatum, in which the invariable stars were fixed, and beyond that was a sphere called the Primum Mobile. This ‘First Movable’ had no luminous body and was therefore invisible to our senses, but its existence was inferred to account for the motions of all the others in the same way that scientists today infer the presence of another body in space by the gravitational effect on the bodies around it.
My father used to drive us mad by telling us not to think about space ‘going on and on and on forever, in case we went insane’, which of course prompted us to think of that exact thing. But whereas space for us today is conceived of as infinite, going on without end, for the mediaeval it was not: space for them terminated at the Primum Mobile. Just as I had suggested to my father that space ended in a ‘wall’, to which he would reply ‘Ah, but what’s behind that wall? More space!’, ancient thinkers also had an answer, as Lewis says:
And beyond the Primum Mobile what? The answer to this unavoidable question had been given, in its first form, by Aristotle. ' Outside the heaven there is neither place nor void nor time. Hence whatever is there is of such a kind as not to occupy space, nor does time affect it.'
Aristotle may not have named this further, but Christian thinkers knew that this could only mean that outside the Primum Mobile was
'the very Heaven', caelum ipsum, and full of God, as Bernardus says. So when Dante passes that last frontier he is told, 'We have got outside the largest corporeal thing (del maggior corpo) into that Heaven which is pure light, intellectual light, full of love' (Paradiso, xxx, 38).
It wasn’t ‘space’ that lay beyond, in other words, but something qualitatively different:
In other words, as we shall see more clearly later on, at this frontier the whole spatial way of thinking breaks down. There can be, in the ordinary spatial sense, no ' end' to a three-dimensional space. The end of space is the end of spatiality. The light beyond the material universe is intellectual light.
It takes something of an effort of will for us in this modern age, in which we have become accustomed to an entirely different view of the universe and the way in which things work, to turn our minds back to a universe in which all power and movement, or what physics would today call ‘forces’ emanate from God: this emanation then sets the Primum Mobile in motion, causing it to rotate; the rotation of the Primum Mobile causes the rotation of the Stellatum, which then makes the sphere of Saturn turn, and so on, down to the last moving sphere - not Earth, we have to remind ourselves, but the Moon.
However, the model was not just a huge, complex clockwork machine: the idea was that within each sphere an Intelligence was attempting to mirror and thereby approach the perfection of the God who was the source of it all. A better image, if we can manage it, might be a giant clock which turned not through the mechanical energy contained in springs but by desire to become: ‘moved’ not in a mechanical sense (though mechanical motion was part of the result) but ‘moved’ as in ‘arousing strong feeling’.
But the really important point comes when one looks back at the world one has left from the perspective of a soul making the journey towards God:
All this time we are describing the universe spread out in space; dignity, power and speed progressively diminishing as we descend from its circumference to its centre, the Earth. But I have already hinted that the intelligible universe reverses it all; there the Earth is the rim, the outside edge where being fades away on the border of nonentity. A few astonishing lines from the Paradiso (xxvm, 25 sq.) stamp this on the mind forever. There Dante sees God as a point of light. Seven concentric rings of light revolve about that point, and that which is smallest and nearest to it has the swiftest movement. This is the Intelligence of the Primum Mobile, superior to all the rest in love and knowledge. The universe is thus, when our minds are sufficiently freed from the senses, turned inside out. Dante, with incomparably greater power is, however, saying no more than Alanus says when he locates us and our Earth 'outside the city wall'.
Thus, instead of beginning with the still Earth and moving outward to ever-larger spheres and a remote and distant God, the entire cosmos ‘flips’: God is at the centre, and we, on Earth, are spinning somewhere on the outer rim. This takes some imagination to grasp in the same way that it was understood a few hundred years ago. Lewis, who has already invited his readers to go outside and look at the night sky twice before, hints that such a glimpse may be needed:
I can hardly hope that I shall persuade the reader to yet a third experimental walk by starlight. But perhaps, without actually taking the walk, he can now improve his picture of that old universe by adding such finishing touches as this section has suggested. Whatever else a modem feels when he looks at the night sky, he certainly feels that he is looking out-like one looking out from the saloon entrance on to the dark Atlantic or from the lighted porch upon dark and lonely moors. But if you accepted the Medieval Model you would feel like one looking in. The Earth is ' outside the city wall'. When the sun is up he dazzles us and we cannot see inside. Darkness, our own darkness, draws the veil and we catch a glimpse of the high pomps within ; the vast, lighted concavity filled with music and life. And, looking in, we do not see, like Meredith's Lucifer, 'the army of unalterable law', but rather the revelry of insatiable love. We are watching the activity of creatures whose experience we can only lamely compare to that of one in the act of drinking, his thirst delighted yet not quenched. For in them the highest of faculties is always exercised without impediment on the noblest object ; without satiety, since they can never completely make His perfection their own, yet never frustrated, since at every moment they approximate to Him in the fullest measure of which their nature is capable.
Mediaevals had their own simpler images to try to capture some of the essence of this:
You need not wonder that one old picture represents the Intelligence of the Primum Mobile as a girl dancing and playing with her sphere as with a ball. Then, laying aside whatever Theology or Atheology you held before, run your mind up heaven by heaven to Him who is really the centre, to your senses the circumference, of all; the quarry whom all these untiring huntsmen pursue, the candle to whom all these moths move yet are not burned.
This Christian view of the cosmos is one which obviously delights Lewis, and which can, poetically at least, delight us. But I think its true power lies for us as moderns in its metaphor: that the universe, seen one way, with goodness and anything that is desirable remote and distant, can suddenly ‘turn’ and become orientated completely differently, centred on the objects of desire, revolving around them perpetually satisfied in the way Lewis describes above.