He was not an especially distinguished pontiff and he didn't reign for very long, yet he is of perennial interest to both academic and popular historians.
The answer can be found in books such as John William Draper's 1874 History of the Conflict between Religion and Science.
In it, Draper characterised the Middle Ages as an era of faith, a time when everyone thought that the Earth was flat.
Draper may have been forgotten, but his narrative lives on.
And that is what makes Gerbert of Aurillac so fascinating.
At a time supposedly devoid of science, here is a medieval pope who was highly proficient in mathematics and astronomy.
In fact, the scientific advance of western Europe began even earlier, when Roman astronomical textbooks were analysed in the court of Charlemagne in the 9th century.
In Gerbert's time, the fruits of Arabic mathematics found their way west. Gerbert himself was part of a circle of correspondents who excitedly discussed the latest developments as they arose.
By the 12th century, the trickle of knowledge from the Muslim and Byzantine empires had become a flood. The works of Euclid, Aristotle and Averroes were translated into Latin and intensively studied at the new universities in Oxford and Paris.
In the 14th century, Europeans surpassed their ancient predecessors by developing theories of impetus and uniform acceleration.
Gerbert played a small but important part in the unknown story of medieval science and Nancy Marie Brown has rightly decided that it is time to highlight his achievements.
Luckily for her, there is a good amount of material for historians to get their teeth into and she has taken full advantage of it.
Brown uses Gerbert's collected letters carefully, aware that they were compiled by an admiring student to present a positive image. She correctly characterises Gerbert as a transmitter of mathematical knowledge without exaggerating his importance.
Arithmetic, astronomy and geometry were a standard part of the curriculum in medieval schools, making Gerbert's enthusiasm for these subjects unusual, but not unheard of.
Brown's demolition of the myth that medieval people believed in a flat Earth is especially welcome.
Brown's Gerbert is neither a saint nor a hero.
Like many senior churchmen of his time, he enjoyed the finer things in life and was as much a politician as a scholar.
His ability to gain promotion from three different emperors, including Otto III who made him pope, shows that he was adept at the courtly arts.
But the political chaos that followed Otto's early death meant that Gerbert had little chance of fulfilling his ambitions.
Brown provides plenty of background information to help readers who may be unfamiliar with the Middle Ages. Unfortunately, she is prone to occasional anachronisms.
She describes Gerbert's geometrical speculations as "experimental" when the modern concept of experiment was alien to the medieval mind. She also believes that scientific progress came to a halt after Gerbert's death in 1003.
Despite debunking many of the legends of the Dark Ages, she can't quite stop believing in them herself.
For her, the worship of relics and intolerant crusaders soon replaced the rationalism championed by Gerbert.
But the medieval world was more complicated than that.
She is right to deplore the pogroms against Jews and the beginning of the inquisition.
Yet Brown seems unaware that within a century of Gerbert's passing, western philosophy reached such heights that historians call the period the "Twelfth-Century Renaissance".
The Abacus and the Cross is a useful corrective to popular prejudice, but it does not go far enough.