Immense practical challenges confronted anybody in the Middle Ages trying to study the literature and history of antiquity. Students of the classics today can consult critical editions of texts prepared by specialized scholars—a body of work that has grown exponentially ever since the humanists of Italy first began methodically to seek out, reconstruct, and study the literature of antiquity in the 14th and 15th centuries. Today’s scholars collaborate with careful editors and reputable publishers, and they supplement their editions of classic texts with user-friendly overviews that discuss the texts’ sources and authors and the historical and literary contexts in which the works were written. For ease of reading and reference, the texts contain title pages, tables of contents, geographical glossaries, maps, diagrams, pictures, explanatory glosses, footnotes, bibliographies, indexes, and recommendations for further study. They are divided into chapters, sections, and paragraphs, and are punctuated in a modern style.

Francesco Petrarch, the prime mover of early Italian humanism, had none of this critical apparatus to help him. Born in 1304, Petrarch traveled far and wide for much of his life in search of classical texts, many of which had lain ignored or little known for centuries in the monastery libraries and private collections of Europe. He met with great success, bringing to light a remarkable number of forgotten texts—and as he realized the vast extent of what had been lost, he grew hot with anger. “Each famous author of antiquity whom I recover,” he fulminated,

places a new offence and another cause of dishonor to the charge of earlier generations who, not satisfied with their own disgraceful barrenness, permitted the fruit of other minds, and the writings that their ancestors had produced by toil and application, to perish through insufferable neglect. Although they had nothing of their own to hand down to those who were to come after, they robbed posterity of its ancestral heritage.

This was an idea that Petrarch would return to repeatedly in his writing. His own era, he argued, was one of intellectual “darkness and dense gloom,” whereas the ancients had lived in a Golden Age of learning. But he held out hope for the future. “There will follow a better age,” he wrote at the end of his Latin epic poem, Africa. “This sleep of forgetfulness will not last for ever. When the darkness has been dispersed, our descendants can come again into the former pure radiance.” Petrarch in essence was here defining the three-part view of European cultural ev­o­lution that dominates historiography today. First comes antiquity, a glorious era of classical learning; then come the Middle Ages, long, lugu­brious centuries of igno­­­rance, feudalism, and plague, when the learning of the ancients gradually disappears; and then finally the Renaissance arrives, and the classics are revived.

But reviving them, Pe­trarch quickly realized, wasn’t going to be easy. The works he rediscovered often were untitled, undifferentiated, un­reliably copied, and incomplete masses of text. Sometimes no author would be mentioned at all; at other times there would be an attribution, but it was wrong, having been mistakenly copied or added by a scribe. Pliny or Seneca might be mentioned as the author of a text without any hint of what we now know: that there were two of each, Pliny the Elder and Pliny the Younger, and Seneca the Elder and Seneca the Younger. Trying to determine the actual age of a text was no easy task either. Even dis­tinguishing between medieval and ancient Latin authors was often problematical.

Petrarch embraced the challenge. What was necessary, he decided, was a sort of literary archaeology—an unprecedented and painstaking effort to locate, dig up, sift through, sort out, clean up, save, compare, contrast, correct, and study the scattered textual remains of antiquity.

It was an inspiring idea. But early on in his studies, Petrarch identified a very basic problem. To appreciate classical literature and history, he realized, he needed to understand the geographical context in which they had been written and had taken place. This presented a host of difficulties. How could one study a history of the Roman campaigns in Gaul, for example, without knowing what the ancients had considered Gaul to be? Without a firm understanding of the ancient world, how could one fully appreciate and draw inspiration from epic poems like Virgil’s Aeneid and Homer’s Odyssey and Iliad, which involved allegorical stories of travel in specific geographical settings?

The shards of ancient geography that Petrarch began to gather and piece together created a picture that was confusing at best, alien at worst—and in many respects almost impossible to square with contemporary reality. The names of ancient towns, rivers, mountains, lakes, seas, countries, and regions had all changed. Old cities had been destroyed, and new ones had arisen. Whole countries, peoples, and empires had come and gone. Parts of the world known to the ancients had dropped off the medieval map, and regions explored since the fall of Rome had been added. Even when continuity actually did exist, it was often hard to discern: scribal errors, compounded over generations by copyists who knew nothing of geography or antiquity, had spawned mutant spellings that varied greatly from manuscript to manuscript, and some had become entirely indecipherable. It was a mess, and Petrarch wanted to clean it up. He described his motivations at the outset of a biographical sketch of Julius Caesar. In focusing on Caesar’s exploits in Gaul, Petrarch wrote, “I believed I should start by describing the [geographical] site of Gaul, where the events had taken place; its description itself has been made in such a confusing manner by some that it prevents an understanding of the facts.”

Petrarch didn’t limit his focus to Gaul. He had something much more ambitious in mind: a full picture of the world as the ancients had known it.

Petrarch worked toward this goal in several ways. One of his first steps, an obvious one, was to seek out whatever geographical information he could find in the encyclopedic and historical writings of the Romans. The most obvious source to turn to was Pliny the Elder’s vast Natural History, a work not well known in Italy at the time but commonly consulted in other parts of Europe. Reading the Natural History, Petrarch noticed that Pliny made several mentions of the work of a first-century geographer almost entirely forgotten in the 14th century: Pomponius Mela, a Roman citizen who had lived and worked in Spain. Petrarch made the search for Mela’s work a part of his book-hunting expeditions, and sometime in the 1330s, possibly in papal circles in Avignon, he found what he was looking for: a copy of Mela’s slender De chorographia, or The Description of the World. Today Mela’s little book is considered the oldest extant Latin treatise on geography. Written far more concisely and elegantly than Pliny’s rambling Natural History, the work immediately appealed to Petrarch, who had a copy made and soon began circulating it among his friends. Along with Pliny’s Natural History, Mela’s Description would become one of the most popular and widely consulted works of ancient geography in the coming two centuries—and almost every copy made during that period can be traced back to the copy Petrarch had made for himself.

For decades Petrarch would rely upon his copies of Pliny and Mela for help in deciphering the places and regions mentioned in classical literature and history. Although his original copy of the Description is lost, his copy of the Natural History survives, and its geographical sections demonstrate just how methodically Petrarch pursued his studies. He annotated the manuscript heavily, in effect creating a rudimentary geographical glossary for himself that ran alongside Pliny’s rambling narrative. When Petrarch came across the names of places and geographical features, he would write them in the margins of the manuscript, creating an easy-to-scan set of names that he could consult as he encountered unclear geographical references in other works.

He also devised a simple system for signaling to himself the kind of geographical object that his marginal annotations referred to. Around the names of mountains he drew a little box that rose to a peak above the word; under the names of rivers he drew a line that rose up vertically to the left of the word; to the left of the names of whole regions he drew a little vertical line; and over the names of cities he drew a line that descended vertically on the left.

Petrarch also marked up many of his manuscripts with notes about geography, one of the most lengthy and revealing of which appears in his copy of The Aeneid. Virgil intended the work to be read as the national poem of the Roman people, and Petrarch and the early humanists understood it as such, giving it a central place in the classical revival they were trying to engineer. Unpacking its geography was therefore a job of critical importance.

The long note that Petrarch made in his copy of The Aeneid appears at the point in the narrative when Aeneas and his sailing companions, having fled Troy, first catch sight of Italy. A harbor reveals itself to them, above which lies something that Virgil identifies as the Temple of Minerva. “The harbor had been formed into the shape of a bent bow by waves blown from the east,” the text reads. “It was hidden by projecting rocks which foamed with salt spray, and from the towered crags its two walls, like drooping arms, ran steeply down. The temple lay back from the shore.”

What was this place? Petrarch threw himself into researching the question, and eventually decided that Virgil had to be describing the Italian coast near Otranto, a port town at the southeastern tip of Italy, situated at the heel of the boot. In his long note, Petrarch explained how he had arrived at this answer.

Many things cause errors concerning the knowledge of places, among them: the inaccessibility of regions to men of our age; the change of names, the rarity and lack of clarity of authors; and sometimes the dissent among them; but above all the lack of intellectual curiosity and the laziness of those who care for nothing that isn’t right before their eyes. Not only the general reader but also scholarly commentators neglect to pause over these things. As for us, as much as we have been able, through a quite scrupulous survey of not only the works of authors, especially cosmographers, but also descriptions of the world and certain very ancient maps that have come into our hands, we have discovered that this place is located at the very corner of Italy, above or beyond Otranto, and is called the castle or camp of Minerva. When one crosses from [the east side of the Adriatic Sea] to the Italian coast, this is the first place that one comes to. Virgil describes this. . . . As concerns this place, either we simply accept the term Temple of Minerva such as it is, because it was the first place sighted [by Aeneas], or, wanting to give the place a name, he [Virgil] used the word temple for castle, transposing one place for another, as was his custom. And indeed there is another place known by this name the Temple of Minerva, although Pomponius [Mela] calls it a promontory on a different shore, as best it can be understood, in [the Gulf of Naples].

These remarks are illuminating on many levels. They lay bare how deeply Petrarch immersed himself in the study of ancient geography—and just how confusing and daunting the whole enterprise must have been. They show Petrarch deploying geography in the service of literary criticism, a defining element of the early humanist movement, and they show him playing different ancient texts and sources against one another, deliberately trying to expose and then resolve their contradictions—another humanist hallmark. He breaks with tradition in another way as well: his remarks show that he was trying not only to revive ancient geography on its own terms but also to understand its correspondence to present-day reality.

In this final regard, Petrarch’s reference to “very ancient maps” is particularly telling. Most scholars agree that Petrarch wasn’t referring to mappaemundi, the grandly symbolic maps popular in the late Middle Ages, because these maps couldn’t possibly have supplied him with the kind of detail he needed to resolve the geographical questions he was trying to answer. The far more likely alternative is that he was referring to marine charts—a relatively new kind of map, made by sailors, that charted the contours of Mediterranean coastlines. Petrarch, it seems, may have considered these charts to be a part of a tradition that extended right back to antiquity. In other contexts Petrarch is known to have relied heavily on marine charts, which he used to help him work out problems of ancient geography and to devise a geographical framework for his own literary creations. Maps, old and new, made armchair travel possible—an idea that meant the world to him as a scholar and a writer. “I decided,” he told a friend in one of his letters, “not to travel just once on a very long journey by ship or on horse or on foot to those lands, but many times on a tiny map, with books and the imagination.”

With books and the imagination: the phrase sums up one of the main ways in which Petrarch approached the study of geography. But it wasn’t the only one. A widely traveled man, Petrarch knew his way around Europe better than almost all of his contemporaries, and he prided himself on his experience as a traveler. “I have been around almost all of the most distant borders of those regions,” he wrote at the beginning of a life of Caesar, “either for leisure and the sole aim of seeing and learning, or on business.” Petrarch felt that his travels qualified him uniquely for the job of deciphering the puzzles of ancient geography—but he also felt that his knowledge of ancient geography could help him expand his understanding of the modern world.

Remote places exerted a special pull on Petrarch, and the search for knowledge about them became for him a powerful metaphor for the humanist undertaking: the vast, collaborative, and never-ending attempt to see and understand the world as a whole (with Rome, of course, at its center). When he learned that his friend Philippe de Vitry, after an extended stay in Italy, had referred to his time there as an “exile” from France, Petrarch wrote to chastise him for his geographical small-mindedness. “Once India used to appear not too distant to you,” he wrote. “At one time with eager mind you used to take measure of Thoprobanes [the quasi-mythical island of Taprobane, in the Indian Ocean] and whatever unknown places exist in the Eastern Ocean. At other times, you used to sigh for Ultima Thule [probably Iceland, signifying the northwestern limits of the world]. . . . In my opinion, you have forgotten that man, who, when asked where he was from, answered that he was a citizen of the world.”

Medieval writers and geographers were generally content to put such places as Taprobane and Ultima Thule wherever there was room for them at the margins of their maps. But Petrarch sought a new kind of precision. If such places really did exist, where exactly were they? Could they be rediscovered? Might finding them again, like rediscovering the lost texts of antiquity, help usher in that much-hoped-for new Golden Age?

Petrarch was never able to pin down the location of Taprobane and Ultima Thule to his satisfaction. But he had better luck when it came to an Atlantic island chain off the northwest coast of Africa known to the Romans as the Fortunate Isles. “Within the memory of our fathers,” he wrote in 1346, “the warships of the Genoese penetrated to them.”

Petrarch didn’t say how he had learned about this expedition, which had been sponsored by Portugal’s King Alfonso IV, but chances are good that he got word of it from somebody close to Pope Clement IV, whom Petrarch knew personally and with whom he had spent time in Avignon. Word about the expedition reached the pope in the early 1340s, and scholars in his circle had quickly associated the newly discovered islands with the Fortunate Isles, evidently after consulting Pliny’s Natural History. Louis de la Cerda, the nobleman to whom the pope granted authority over the islands, certainly had Pliny in mind when he wrote to the pope in 1344. De la Cerda made a point of identifying himself as the “prince of Fortune” and then listed the islands under his control as “Canaria, Ningaria, Pluviaria, Capraria, Iunonia, Embreonea, Atlantia, Hesperide, Cernent, Gorgonide, and Galeta.” The first six of these names correspond directly to Pliny’s names for the Fortunate Isles, and the rest correspond to islands that Pliny located in nearby waters—islands, presumably, that de la Cerda intended to locate and bring under his control. We know them today as the Canary Islands.

La Cerda’s letter reveals that an important new trend was under way in Europe. The Latin Church and the European nobility were beginning to rely on ancient geographical ideas to help them develop a modern program of Atlantic exploration and imperial expansion—and, conveniently for Petrarch and his friends, the trend dovetailed with the emerging humanist effort to revive the learning, power, and geographical reach of Rome.

One of Petrarch’s most important disciples was the Florentine author and scholar Giovanni Boccaccio. Like Petrarch, Boccaccio is today celebrated as one of the founding fathers of Italian literature and is best known for his bawdy Decameron and his vernacular poetry. But in his own day Boccaccio made a name for himself as an authority on ancient geography—and his is the sole surviving account of King Alfonso’s expedition to the Canaries.

Boccaccio’s most important contribution to the humanist study of geography was a work almost entirely forgotten today: a reference dictionary, widely circulated and relied upon in his time, titled On Mountains, Forests, Springs, Lakes, Rivers, Swamps or Marshes, on the Names of the Sea. In preparing his dictionary, Boccaccio pored over ancient geographical texts, medieval mappaemundi, marine charts, and the accounts of contemporary travelers—and, not unlike Petrarch, he staggered away from them all, reeling at the immensity of the mess. The ancient authors contradicted one another in a dizzying number of specifics, scribal errors had muddled everything, and the regions of the world known to the ancients and the moderns didn’t fully overlap. These weren’t new problems, but for the most part, ancient and medieval writers hadn’t grappled directly with them and instead had simply recorded everything that they had heard reported or rumored about the world. This wasn’t good enough for the humanists.

By marking up his copy of the Natural History, Petrarch had created a geographical glossary of sorts, but it was unwieldy and intended only for his personal use. Boccaccio’s On Mountains re­presented the next logical step: a single easy-to-use volume devoted to the geography of antiquity that could be copied and consulted by anybody interested in classical history and literature. Boccaccio’s authorities were the ancients, and he combed through their texts with great care as he prepared his dictionary, but he also examined modern sources. Like Petrarch, he looked to marine charts as a way of resolving in­con­sistencies he found in classical texts, and he spent considerable time comparing the geographical accounts of recent travelers with those of ancient authorities. In the works of medieval travelers, for example, he read that the Caspian Sea was landlocked—a claim contradicted by such ancient authorities as Pliny, Mela, and Isidore of Seville, all of whom wrote that it emptied out into the open sea in the north. The bodies of water that the modern and ancient writers described just didn’t seem to be the same. “I discovered that there are two Caspian Seas,” Boccaccio wrote in exasperation. “One is located in the middle of the land and has no connection with the ocean, while the other flows from the ocean.” Rather than take sides on the issue, Boccaccio decided to include two separate entries on the Caspian in his dictionary. “Which one of these opinions is true?” he asked. “I leave it to be examined by those more diligent than I, since I dare not remove my confidence in the ancients, nor can I deny the eyewitness testimony of the moderns.” This problem—how to square ancient and modern descriptions of the world—would consume humanist geographers for centuries to come.

During the 1350s, Boccaccio maintained a journal in which he jotted down notes to himself, and copied out classical quotations and excerpts that he thought might be useful to him in his studies and his writing. In most respects the journal represents an idiosyncratic collection of the work of classical writers, but at one important point in the middle of the journal, in an entry that dates to the 1350s, Boccaccio recorded a contemporary development: King Alfonso’s expedition to the Canaries. Boccaccio had come across the account of the expedition sent back to Florence from Seville, and the story captured his attention. Summarizing in Latin what he read in the merchants’ correspondence, Boccaccio produced a short description of the episode that in subsequent years would take on a life of its own among Florence’s humanist scholars, who knew it under the title Of Canaria and Other Islands Recently Discovered in the Ocean Beyond Spain.

Boccaccio didn’t just boil down and translate the merchants’ account. Instead, he recorded those parts of the account that to him seemed to make it clear that the islands being described were the same as Pliny’s Fortunate Isles. Both Boccaccio and Pliny write of a chain of mountainous islands, some inhabited and some uninhabited, located off the coast of northwest Africa. Both mention the presence of simple human dwellings and a small temple. Both describe the islands as being rich in figs, palms, and birds. Both single out three islands for special attention: a perpetually rainy island, one entirely covered with strikingly tall trees, and a giant mountainous one apparently capped with snow. This last is known today as Tenerife, which rises to more than 12,000 feet above sea level. Boccaccio’s use of the name Canaria, too, is an obvious interpolation based on Pliny’s use of the name; the island’s inhabitants certainly wouldn’t have used it. Boccaccio and Pliny both described the native inhabitants of their islands in the same way: a happy, intelligent, communally minded people who live in a setting of natural abundance, far from the cares of civilization.

Boccaccio wasn’t the first to make these connections. At the outset of On Canaria he referred to “these islands we generally call ‘rediscovered,’” language that suggests plenty of others were thinking along similar lines. By sailing out into the Atlantic, by studying old books and new maps, merchants and scholars alike had begun to expand their horizons to include long-lost places that had been known to the ancients—and they had every reason to believe there were more of them to be found. In On Canaria, Boccaccio summed up this new spirit of discovery, which in the coming century and a half would carry Europeans south around Africa and west to the New World.

“The more they advanced,” he wrote, describing the progress made by Alfonso’s sailors out into the islands of the Atlantic, “the more of them they discovered.”