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Out of Darkness

Book review: The Abacus and the Cross: The Story of the Pope Who Brought the Light of Science to the Dark Ages


Published March 2, 2011 at 6:35 a.m.


What springs to mind when you hear the phrase “the Middle Ages”? Perhaps something like the scene from Monty Python and the Holy Grail in which chanting monks methodically whack their own heads with two-by-fours. The idea of medieval times as dark and dominated by an anti-intellectual Catholic Church seems to persist no matter how hard historians try to correct the record.

Science historian Nancy Marie Brown, who lives in East Burke, contributes her effort in The Abacus and the Cross: The Story of the Pope Who Brought the Light of Science to the Dark Ages. Written for both history and science enthusiasts, the book rehabilitates a wrongly maligned era through the story of a single, particularly learned figure: Gerbert of Aurillac, a peasant who became Pope Sylvester II in the year 999.

Gerbert lived at a time when scholarly learning, then centered in Baghdad, was just starting to leak into the Western world via Islamic Spain. Arabic scribes were saving Euclid, Aristotle, Ptolemy and the like from historical oblivion, and Latin translations of those Arabic translations were finding their way across the Pyrenees by request of Christian churchmen, who were expected to be schooled in the sciences and arts. Aurillac, as it happened, was just over those mountains, in southwestern France. Gerbert was in the right place at the right time.

Plus, he was smart. As a young monk, Gerbert had exhausted the resources of his local monastery (religious centers being the only path to education in his time) by the age of 17. He spent the next three years studying in the Catalan region of Spain, recently rewon from the Islamic caliphate. That may have been where Gerbert came across a book by an Islamic scholar about the numbering system we know as Arabic (which, as the Arabs knew, actually came from India). Arabic numbers would have been entirely new to Westerners, who still used Roman numerals. Brown contends that, in his subsequent position as head schoolmaster at the famed Reims Cathedral, Gerbert was responsible for introducing the West to the numbering system we use today.

Whether the sole purveyor of this momentous change or not, Gerbert did teach math for 24 years at Reims using an abacus labeled with Arabic instead of Roman numerals — a hand-drawn copy of which came to light in 2001. The drawing, circa 993, depicts a board inscribed with columns, over which one shuffled counters made from cow’s horn, and marked with “nine signs” — that is, the numbers 1 to 9, plus zeros for place holders.

Gerbert most likely also used an equally complex astrolabe, Brown writes, to predict the positions of the stars, tell time and measure geologic distance, among other things. The astrolabe remained the world’s most popular astronomical instrument until the telescope appeared in 1610. Brown meticulously describes how this and Gerbert’s other teaching instruments actually worked. But her main point is to show that 10th-century church leaders knew the Earth was round and, with the astrolabe, could even calculate its circumference with surprising accuracy. Such study was God’s work, they believed, citing the Book of Wisdom: “Thou hast ordered all things by number, measure and weight.”

“Then Martin Luther took the Book of Wisdom out of the Bible in the sixteenth century, relegating it to an appendix,” Brown writes in one of several sweeping summaries she uses to tie her subject to the current era. “It was deleted altogether in Protestant Bibles of the nineteenth century — which may be one reason why many Americans today consider science and religion antithetical: No longer does math reveal the mind of God.”

Brown’s historical account draws from — and reads carefully between the lines of — a typically scant medieval record. (Umberto Eco’s famous depiction in The Name of the Rose of a medieval library going up in flames comes to mind.) Primary sources include Gerbert’s letters, copied by him and an adoring student, and the “very messy rough draft” of Richer of Saint-Rémy’s History of France, written in the 990s and stored in a cathedral library until it was discovered in the 1830s. Many sources exist solely because the medieval practice of bookmaking reused older parchment to paper the inside covers.

This palimpsest record seems to have inspired Brown to a similarly layered style: She provides extensive context and backstory for each new proposition about Gerbert. Her digressions are fascinating. In one, she tells the story of Dennis the Humble, a lowly monk and church calendar copier who decided in the 500s that he would date things from Christ’s birth, anno Domini (the year of our Lord), or AD, instead of from Emperor Diocletian’s reign. Two hundred years passed before his idea even began to catch on with the rest of the church.

The last third of the book, on Gerbert’s shaky rise from schoolmaster to the papacy, reads like a dutiful appendix. Gerbert made no scientific or scholarly advances while he was absorbed in the politics of the Holy Roman Empire, and Brown’s interest clearly lies in the medieval origins of modern scientific thought. She coauthored an award-winning book on Gregor Mendel, the first scientific grower of genetically modified food, and wrote a history of a medieval Viking woman’s cross-Atlantic travels.

As a whole, though, The Abacus and the Cross conveys a rich picture of how the church promoted, rather than suppressed, learning in the Middle Ages. At the center of its operation were books, acquired through an open exchange with Muslims. A century later, the church would be embroiled in war with these “demons,” beginning with the first Crusade in 1096 — a turn of events that left its own lasting legacy of misunderstanding. But in Gerbert’s countless requests for copies of books in his letters to students, archbishops and counts, there is evidence of a world of learning.