The modern mind has been trained to regard the Middle Ages as backward and unenlightened. “The Oxford English Dictionary” defines the word medieval as something that is “very old-fashioned or primitive.”

This is reflected in popular entertainment. Three major films were released last year about the medieval world and its supposed backwardness.

Director David Lowery’s “The Green Knight,” director Ridley Scott’s “The Last Duel,” and director Paul Verhoeven’s “Benedetta” portrayed the Middle Ages as misogynistic, dirty, anti-scientific, superstitious, hypocritical, and cruel.

These directors overstate their case. The medieval era was not entirely so. The millennium between 500 and 1500 was a period of intellectualism, poetry, and moral consideration, as seen in the works of great writers such as St. Thomas Aquinas, Dante Alighieri, Lady Julian of Norwich, Geoffrey Chaucer, and Sir Thomas Mallory.

A Wyoming Catholic College professor, Jason M. Baxter, is one of a growing contingent of dissidents in the academy fighting against the stigma. His new book, “The Medieval Mind of C.S. Lewis: How Great Books Shaped A Great Mind,” is an excellent introduction to the medieval worldview.

It is both a biography and an exploration of the literature and cosmology of the Middle Ages. 

A Christian apologist and Oxford tutor, Clive Staples Lewis is well regarded today as the preeminent Christian intellectual of the 20th century. He wrote popular books such as “Chronicles of Narnia,” “Mere Christianity,” and “The Screwtape Letters,” to help fill a void in academic Christian writing at a time when the academy was obsessed with contemporary intellectuals like Sigmund Freud and Charles Darwin.

Mr. Baxter brings light to what he calls “the third Lewis” — neither the children’s fantasy writer nor the apologist but the academic who wrote university textbooks on classical poets such as John Milton and Edmund Spenser.

“This was the man who read fourteenth-century medieval texts for his spiritual reading, carefully annotating them with a pencil; who summed himself up as chiefly a medievalist,” Mr. Baxter writes.

He calls Lewis the “British Boethius,” comparing his work to that of the catholic philosopher translated ancient philosophers into Latin for preservation during the declining years of the Roman Empire, St. Boethius. 

Lewis saw himself as a resident of the Middle Ages. Mr. Baxter claims that Lewis considered the modern world to be filled with barbarians who had forsaken the wisdom of the past. His bibliography reflected his desire to preserve ancient wisdom.

“His own age was one of proletarianism, which was now, in a way similar to Boethius’s barbarians, cut off from the classical past and proud of its distance from classical antiquity,” Mr. Baxter writes. 

The world that Lewis preferred is different from the modern view of the universe.

Medieval cosmologists did not look into space and see the dead vacuum or the infinite void. They saw a sprawling and orderly cosmos that reflected the infinite nature of God, what Dante describes in his poem “Paradiso” as, “the love that moves the sun and other stars.”

Mr. Baxter writes, “in contrast to the modern conception of the world, which imposes on the mind a sense of being lost in infinite and vast space … if we look up into the sky with medieval expectations in mind, then we will feel it both as finite but also pushing down on us.” 

Medieval cosmology viewed the universe as a harmoniously ordered symphony, comparable to the grandeur of a cathedral. It was a dreamlike vision that “inspires contemplation of the deep patterns built in it by the craftsman.” 

Lewis disliked the cosmology that the scientific revolution imposed upon the universe, dismissing it as a moral desert, “flavorless, odorless, and colorless, a series of interlocking microstructures whose various mathematical extensions and motions create within the human mind different subjective impressions,” as Mr. Baxter writes. 

The medieval era was neither backward nor superior. It was complicated. The great poets like Dante and Chaucer captured this well, exploring the ways medieval peoples chafed against authority and tradition. 

“The Medieval Mind” does not defend mysticism or luddism. It does defend the medieval model of the universe as “wrong, strictly speaking,” but reflective of a painful loss of the desire for beauty and meaning. 

Mr. Baxter and Lewis remind us to avoid chronological snobbery and that we dasn’t avoid taking the middle ages seriously.