“We have been inoculated against the influenza here,” C. S. Lewis wrote to his father, in November 1918, as the Spanish flu pandemic raged. “If it is at all bad at home [in Belfast] I should get it done. It is not worth … risking one’s life over a thing like that and the inoculation is very mild. It proved an effective check in Paris and why it has not been more widely used here [in England], goodness only knows.” It is safe to assume that Lewis would not have been an “anti-vaxxer” if he had lived to see the Covid-19 pandemic. He would have “followed the science,” as today’s phrasing has it. And yet he was by no means credulous regarding the claims of “science.” Though often remembered for his stories and apologetic arguments, Lewis spent much of his career thinking about what science could reveal to us about reality, and – perhaps more importantly – what it could not.

Though no scientist himself – his professional expertise was language, literature, and philosophy – Lewis had a sincere respect for science and was reasonably knowledgeable about certain departments of it, especially cosmology and physics. He had a particular interest in multi-dimensionality and the nature of time. He read works by Sir James Jeans, Sir Arthur Eddington, Sir Fred Hoyle and others, keeping tabs (from an admittedly amateur perspective) on developments in astronomy. Among Lewis’s Oxford colleagues was the Nobel Prize–winning physicist, Erwin Schrödinger, whose famous thought experiment gave the world a cat that was simultaneously dead and alive. One can only imagine the sort of conversations the two men had in the Senior Common Room at Magdalen College in the 1930s. No record of their interactions has come down to us, but Lewis evidently valued the association and even mentions Schrödinger in his novel Out of the Silent Planet.

Lewis’s attitude toward science, though very positive and respectful, was not uncritical. He believed that science, like all human enterprises, has its limits and that those limits needed to be understood and observed not only for the sake of other disciplines but for the sake of science itself. In The Abolition of Man, Lewis deprecates “unscientific followers of science”: those who overvalue the scientific method or accept scientific pronouncements without question. He argues that these people may suppose themselves to be devotees of the discipline, when in fact, they are undermining it from within. As an intellectual historian and an interested observer of scientific developments, Lewis often took aim at this error.

The longest book Lewis ever wrote was the seven-hundred-page English Literature in the Sixteenth Century excluding Drama. It was his contribution to a multivolume series called the Oxford History of English Literature – “O Hell!” as he nicknamed it. The book opens with a detailed discussion of “the new astronomy” that was first theorized by Copernicus and later verified by Galileo. This astronomical revolution gave human beings a new home address, transferring Earth – planet Earth as it was now known – from the center of the universe to its circumference. The Sun no longer went around the Earth, but vice versa. The cosmos had become heliocentric. Lewis concludes that what proved important about the new astronomy was not the mere alteration in our map of space, but the new use made of mathematics in making sense of nature. Thanks to the invention of new scientific instruments, such as the telescope (invented early in the seventeenth century), astronomers could observe the stars and the planets with a much greater degree of accuracy. They could measure very precisely how far away these celestial bodies were from one another and from Earth. They could measure how quickly they moved. Eventually, they could even measure how much these bodies weighed.

These measurements were represented, naturally enough, through the use of numbers, and so began the process of “reducing Nature to her mathematical elements,” as Lewis puts it. He writes in The Abolition of Man that the night sky is “stripped of its qualitative properties and reduced to mere quantity.” This new reliance upon mathematics is demonstrated in the change of language used by the astronomer Johannes Kepler (1571–1630), who, at the start of his career, explained the motion of the planets by reference to their animae motrices (motive spirits), but by the end of his career explained it mechanically.

The result of these changes was that the word “scientific” came increasingly to denote that which was measurable, mathematical, mechanical. Science means “knowledge,” and knowledge now means “knowledge of numbers.” Thus the way was paved for the clockwork universe of Sir Isaac Newton and his “laws” of motion. People came increasingly to think of nature as regular and impersonal, more like a machine than an organism, more like a book of statutes than a book of pictures. The new scientific method introduced into the human imagination a paradigm that was based on calculations, equations, statistics. Once upon a time, nature had been viewed as a body rather than as an engine. Nature had teemed with humors, influences, and the four elements (earth, air, fire, and water) disposed in particular realms or homes. But that older view was discarded. Hence the title of Lewis’s last academic book, The Discarded Image. Ancient rhythms have been replaced by algorithms.

And all very good too, you might say! This process of quantification represented an improvement in clarity of thought, did it not? What had Kepler meant when he attributed the motion of the planets to their motive spirits? Wasn’t that just a way of saying that he didn’t really understand their motions? What was gained by introducing “spirits” into the picture?

There is truth in this critique of premodern science. It is hard to say what was gained by introducing “spirits” into astronomy, but it is also worth investigating what precisely we have gained by speaking only in terms of number. We have acquired precision of a kind, yes. We have acquired a certain capacity for prediction. Those things are worth having, Lewis agrees, but let us not overbalance and conclude that a numerical approach will tell us everything worth knowing about the cosmos.

With disarming simplicity, Lewis invites us to consider three different ways of describing a wintry night, in his essay “The Language of Religion” in Christian Reflections. We could say simply, “It was very cold.” Or we could say, “There were thirteen degrees of frost.” But there is a third way too. We could say:

Ah, bitter chill it was!
The owl, for all his feathers was a-cold;
The hare limped trembling through the frozen grass,
And silent was the flock in woolly fold:
Numb were the Beadsman’s fingers …

The first description is what Lewis calls ordinary language. The second is scientific language. The third, quoting John Keats’s “The Eve of St Agnes” written in 1819, is poetic language. Each linguistic register has its own merits and limits.

The first great merit of the scientific description is precision: it quantifies coldness according to recognized units of measurement and as a result various conclusions can be drawn, for instance, about whether the early spring cabbages are going to be damaged by the frost, or whether I might need to allow extra time tomorrow morning for defrosting the windshield of my car. The second great merit of the scientific description is that it is univocal – it means only one thing. The standard used in measuring coldness can be made international; it can serve as a universal language. The world over, “2 + 2 = 4” means exactly the same thing. Nothing is lost in translation from one tongue into another. Lewis frankly acknowledges that, in this sense, “Pure mathematics is the type of successful thought.”

However, for all its merits and success, scientific language also has limits. It doesn’t help us to understand the quality of a cold night; it won’t tell us what we shall be feeling if we go outside. If we have lived all our lives in tropical climes and don’t know what a hard frost is like, we won’t be much the wiser on learning that there are thirteen degrees of frost. What is frost to someone who has never encountered it? What is a degree of frost? Ordinary language would be more helpful in explaining the situation: “Your ears will ache … you’ll lose the feeling in your fingers” etc. The word numb will convey more than any number.

However, what Keats tries to convey in his poem can’t be rendered as a thermometer reading. It is not univocal or universal; we can’t translate his poem into, say, Japanese without loss or at least alteration. And yet if we want to know just what it feels like to go outside and breathe the bitterly chill January night air, Keats paints for us a very vivid and sensible picture. He communicates knowledge to us that the ordinary and scientific ways of speaking leave out.

In other words, poetry is a kind of knowledge, and since knowledge is a synonym for science we could quite legitimately say – if we wanted to – that poetry is a branch of science. Lewis, as it happens, does not want to dissolve science and poetry into a single thing. He happily recognizes that science now means knowledge attained by experimentation, observation, mensuration, and so forth. We do well to distinguish different kinds of knowing and different ways of speaking. But Lewis wants to remind us that modern science is only one kind of knowledge among many.

Science deals in a kind of knowledge that is quantifiable and measurable, and instrumental. If your instrument – your thermometer – tells you that there are thirteen degrees of frost, and if it is working properly, you will know to cover up your cabbages and make sure that you have the windshield scraper handy. Scientific statements of this sort are easily verifiable or falsifiable; they are, as Lewis puts it, “more easily ‘cashed’” than statements made either in ordinary language or poetic language. “But the poet might of course reply that it always will be easier to cash a cheque for 30 shillings than one for 1,000 pounds, that the scientific statements are cheques, in one sense, for very small amounts, giving us, out of the teeming complexity of every concrete reality only ‘the common measurable features’.”

It’s interesting that Lewis should here specify thirty shillings. Of all the numbers he could have chosen for this illustration, he selects thirty, which is surely no accident. We should detect a subtle allusion to the example of Judas, who betrayed Jesus for thirty pieces of silver (Matt. 26:15). Judas kept the money bag and stole from it (John 12:6), and it is often easier to steal small amounts than large ones. Judas, so very good with numbers, was like Oscar Wilde’s definition of the cynic: he knew the price of everything and the value of nothing.

Lewis is certainly not implying that scientists are traitors or cynics. But I suspect he is wanting to engage in a little healthy iconoclasm, to remind his readers (by means of that poetic device called connotation) that science, as a branch of knowledge, speaks a finite language. Any language – be it ordinary, scientific, or poetic – has parameters. To push a language beyond those parameters is unwise, for then you are trying to make it live where it does not belong. Remarking on the history of science, Lewis admits in The Abolition of Man that

The stars lost their divinity as astronomy developed … But that is not the whole story. It is not the greatest of modern scientists who feel most sure that the object, stripped of its qualitative properties and reduced to mere quantity, is wholly real. Little scientists, and little unscientific followers of science, may think so. The great minds know very well that the object, so treated, is an artificial abstraction, that something of its reality has been lost.

Categorizing the world in these abstract, quantitative ways makes the universe less real. It is a point that Lewis expresses memorably in one of his Chronicles of Narnia, The Voyage of the Dawn Treader, where the boy Eustace, on meeting a living star, remarks, “In our world, a star is a huge ball of flaming gas.” To which the reply comes, “Even in your world, my son, that is not what a star is but only what it is made of.”

It is a proper use of the astronomical intellect to describe things in terms of matter and motion, to say that a star is comprised of so much hydrogen and helium, weighing so much, with such and such dimensions, moving at a measurable speed through space, at a particular distance from Earth. But having made all these quantifying observations, have we said all that there is to be said about the star? Have we said why it was made? Have we said who made it, if anyone? Have we explained how it makes us feel when we see it in the night sky?

Personal and purposive descriptions are not available in language that is merely quantitative. Yet we are persons, and we have purposes. To erase ourselves and our intentions from our language is to make it less fully alive. And because language is an expression of ourselves, we become less fully alive too; we become a little bit dead, more like Schrödinger’s cat than we were before. To quote Lewis’s friend Owen Barfield in his influential work Poetic Diction: “Of all the devices for dragooning the human spirit, the least clumsy is to procure its abortion in the womb of language.” Our knowledge – that is, our science – thus becomes attenuated, less able to apprehend life in all its fullness.

To prune the dead wood in our language, we must use it more carefully by adopting the right register for the right situation. It can be extremely useful to analyze nature in terms of quantity, only not when we wish to understand its quality. We must not confine ourselves to the language of number because, if we do, our world will shrink to something needlessly small and numb.

The smallness of scientific statements is often obscured by their successfulness. Scientific statements succeed in defining and predicting certain pockets of the natural world, definitions and predictions which can then be put to use – in building the internal combustion engine or devising the microchip or developing a vaccine for Covid-19. The magnificence of such scientific achievements is so huge that it can mislead us into thinking that they have said a great deal, when actually they have said relatively little, but said it very well. A true scientific statement has to be relatively small, because it’s only relatively small things that can be said with sufficient precision to be empirically verifiable or falsifiable.

It might sound preposterous to describe the mapping of the human genome as a “small statement,” but genetics is only one department of biology, and biology is only one department of science, and science is only one department of human knowledge. Seen in the context of all that could possibly be said about a human being – biologically, socially, economically, historically, geographically, psychologically, spiritually – any genetic statement, however marvelously correct, is still a minuscule fraction of the total. We can “follow the science,” but only so far. When we start trying to make larger statements we move into the language of the humanities, and then into the arts, and finally into religion.

Religious statements, by saying things which attempt to explain life in the round, use language that is very hard to quantify, to measure, to test, but that’s because they are trying to say a very great deal. Religious language seeks to find the unity, the oneness, the heart of all reality, which includes persons and purposes and qualities and even destinies. Religion comes from Latin religio, the bond, the ligament or ligature that ties things together. Here the stake is not a mere thirty shillings, but every penny you have. Your entire life. Your very soul.