In season 6 episode 2, Paul and Courtney discuss Lewis’s first book in the Ransom Trilogy, a book titled Out of the Silent Planet.
We are introduced to the main character, Elwin Ransom, a university professor and philologist, who is on a walking holiday in England. He stumbles upon an acquaintance one night when he is looking for food and shelter, and that acquaintance and his friend—Dr. Weston and Dick Devine—drug and kidnap Ransom and stow him on a space ship on its way to the planet Malacandra (or Mars). On his way to Malacandra, miles from Earth, Ransom begins to realize the seriousness of his situation, and the result is terror. And the source of this fear is that fact that he is in space. As Ransom asks Weston at the beginning of chapter four, “You mean we’re—in space.” And then: “Ransom uttered the word with difficulty as a frightened child speaks of ghosts or a frightened man of cancer” .
But then Ransom undergoes a drastic change in perspective as he looks out into the marvelous scene before him. He begins to realize the universe—space—is much different than he’d been told. This highlights the “mental switch” that Lewis is after: he thinks that the current way of looking at the universe, the so-called “New Astronomy” has resulted in a disenchanted way of viewing the world. Lewis wants us to begin to conceive once again the world as the heavens and the earth, not the space and the earth.
As Lewis discussed in his monumental 700 page work entitled English Literature in the Sixteen Century Excluding Drama (1954), this newly developed astronomy didn’t just alter our map of the cosmos (something he agrees needed to change), but also our methodology for verifying our model. As he wrote,
By reducing Nature to her mathematical elements [the new astronomy] substituted a mechanical for a genial or animistic conception of the universe. 
The new paradigm for understanding the universe was in terms of mathematics and mechanism. The older view of the cosmos as a kind of organism teeming with life, dance, influences, elements, order was abandoned, Lewis describes this shift from a medieval to a modern conception in The Discarded Image as follows:
Hence to look out on the night sky with modern eyes is like looking out over a sea that fades away into mist, or looking about one in a trackless forest—trees forever and no horizon. To look up at the towering medieval universe is much more like looking at a great building. The ‘space’ of modern astronomy may arouse terror, or bewilderment or vague reverie; the spheres of the old present us with an object in which the mind can rest, overwhelming in greatness but satisfying in its harmony .
One the earlier model, we imagine ourselves as part of a rich and genial universe full of life, dancing, and ceremony. On the new model we find ourselves adrift in a vast see of nothingness.
However, we ought to return to the old model. The solution is to understand the distinction between space and the heavens and utilize both. More specifically, conceiving of the world according to the medieval model and in terms of the heavens, we begin to re-imagine the world as a place full of not just quantity (and there are lots of stars and planets in space), but in terms of “quality” (whatness) and “quiddity” (thatness). This will push against the modern tendency and imagination to reduce everything to its constituent bits or parts and we begin to appreciate the things of this world.
- Christiana Hale, Deeper Heaven: A Reader’s Guide to C. S. Lewis’s Ransom Trilogy
- S. Lewis, English Literature in the Sixteen Century Excluding Drama
- S. Lewis, The Discarded Image
- S. Lewis, Out of the Silent Planet
- S. Lewis, The Voyage of the Dawn Treader
- Blaise Pascal, Pensées
- Michael Ward, “Imagine There’s No Heaven?: C. S. Lewis on Making Space for Faith,” in The Story of the Cosmos: How the Heavens Declare the Glory of God
-  C. S. Lewis, Out of the Silent Planet, 27.
-  C. S. Lewis, English Literature in the Sixteen Century Excluding Drama, 3.
-  C. S. Lewis, The Discarded Image, 99.