notes on the core map   |   notes on the Dati T-in-O map  

Notes on the core map
World map by Donnus Nicolaus Germanus, after Claudius Ptolemy, from Ptolemy's Cosmographia (Ulm: Leonhart Holle, 1482).

The most important geographic and cartographic source of the European Renaissance was actually compiled in the Second Century, C.E. (A.D.), by the Greco-Roman scholar Claudius Ptolemy (or Ptolemaeus; ca. 90-168), who lived in the Egyptian port city of Alexandria, home of a marvelous ancient library that was destroyed in the Third Century. Ptolemy is best known to the modern world as the "author" of the prevailing medieval theory that the Earth was the center of the Universe. The theologically satisfying "Ptolemaic" system remained essentially unchallenged until the publication in 1543 of Copernicus's De revolutionibus orbium coelestium, which demonstrated that a Sun-centered model of the universe more accurately described the perceived movements of the heavenly bodies.

Ptolemy's astronomical calculations and theories, as well as some of his geographical ideas, are laid out in the Almagest-a name applied by Arabic scholars who preserved the work for the modern world. The Almagest was translated into Latin, the written language of Western medieval scholars, in the Twelfth Century. Ptolemy's great geographical work, the Geographia (also known as the Cosmographia), however, was not translated into Latin until the early Fifteenth Century. Its "rediscovery" caused a sensation among European cosmographers, in time completely reforming their views of the World and their methods of mapping it. Though Europeans still communicated ideas without the benefit of printing presses, Ptolemy's Geography was something of a bestseller. It was reproduced in hundreds of manuscript copies, and after book printing was introduced to Europe around 1440, the Geographia was one of the first scientific books to be published. A first edition was published without maps in Vicenza, Italy in 1475. A Bologna edition with maps followed in 1477, and four more editions appeared by 1500, a large number for an illustrated work in the Fifteenth Century. A German scholar published this map in 1482 in Ulm, on the Danube River in the modern state of Baden-Württemberg.

Ptolemy's Geographia influenced the reform of the science of geography during the Renaissance in at least two major ways. First, it impressed upon Europeans the desirability and practicability of compiling maps by means of mathematics. Ptolemy wrote that "It is the great and exquisite accomplishment of mathematics to show all these things to human intelligence." The Geographia explained how the surface of the spherical Earth could be projected usefully onto the flat surface of a map by means of simple drawing tools and a rudimentary knowledge of geometry. Ptolemy explained how to construct no less than three map projections. For regional maps, he recommended a rectangular projection developed by another Greek scholar named Marinus. This simple projection has parallels and meridians running at right angles to each other like the lines of graph paper. Another projection of Ptolemy's own invention (called Ptolemy's "First Projection") had straight meridians converging at a theoretical point somewhere to the north of the North Pole. Parallels curved roughly as they did on the surface of the Earth around this geometrical center. This projection overcame many of the severe scale distortions (especially towards the poles) that Marinus's rectangular projection produced. And because the meridians appeared as straight lines, it was still relatively simple to plot on it points of known latitude and longitude. This is the first description of a family of projections modern cartographers call "conic." They are made by projecting a theoretical light source in the center of the globe through the surface of the Earth onto a theoretical cone wrapped around it; the cone is then "unwrapped" to produce a flat map. They are used mostly today precisely as Ptolemy suggested-to map large portions of the Earth's surface, mostly at mid-latitudes.

Ptolemy's "Second Projection" was used to prepare our core map. It was harder to draw, because its parallels and meridians were both curved, but it reduced scale distortions even more and yielded a map that more nearly simulates the curvature of the Earth. It is now called a homeotheric projection, meaning equal area, because it attempts to show the relative sizes of different parts of the world in true proportion to each other. Ptolemy preferred this projection, but only a few geographers in the Fifteenth Century had the patience to prepare maps with this projection. One of them was a Benedictine monk named Donnus Nicolaus Germanus, a prominent late Fifteenth-Century editor and interpreter of Ptolemy, who is the actual author of this world map, as well as of the 26 regional maps that appear in the Ulm edition of the Geographia.

This leads us to the second major contribution of Ptolemy to Renaissance geography-"his" maps. It turns out that no maps survive that can actually be attributed to Ptolemy. The maps that appeared in this volume, and most other editions of the Geographia, are all more or less copies of a set of 27 (including maps of parts of Europe, Asia, and Africa) that were added to the text by Byzantine or Arab scholars sometime before the end of the Thirteenth Century. We don't know if Ptolemy himself had ever drawn anything like them, but the geographic data upon which they were based is indisputably his. In any event, they were more comprehensive and more geometrically precise than anything else Europeans had yet produced or seen. The regional maps, as well as the world map were compiled primarily from an extensive database that forms the major part of "Books" 2-7 of the Geographia. Page after page of tables supplied the latitudes and longitudes of places all over the ancient world. This database and the maps drawn from it inspired imitation by scholars who comprehended Ptolemy's methods and wished to update his information. Germanus, for example, added several tabulae modernae (modern maps) to his version of the Geographia. The Ulm edition includes Germanus's maps of the Iberian Peninsula, France, Scandinavia, Italy, and ancient Israel substitute the title on the map itself.

For the most part, the places appearing on the Ptolemy-Germanus world map are given their ancient names, taken from Ptolemy's tables of places and coordinates. The most important concession to the passage of almost thirteen centuries between Ptolemy and Germanus was the addition of Scandinavia-a feature poorly known by ancient Greeks and Romans, but too significant to Fifteenth-Century Europeans to have been omitted from this map. In all other respects the map retained Ptolemy's Second-Century Mediterranean perspective. North Africa appears in some detail, and there is a reference to the legendary sources of the Nile in the Mountains of the Moon. Southern Africa lay beyond the reach of Ptolemy's data and geographical imagination. There is a suggestion that a large southern continent connects Africa with Southeast Asia, and encloses the Indian Ocean ("Mare Indicum"). But all of the land south of the Tropic of Capricorn is called "terra incognita." Asia ends abruptly in the East in the vicinity of exotic China; and the Indian Ocean appears as a closed inland sea.

Surrounding the map image itself are personifications of twelve winds. It was a common medieval and early modern device to equate compass directions with the winds that blew from them. We might see them as decorative curiosities, but to the maritime world of the Renaissance Europe, these were important geographical features. Note that each is given a specific name, a personality that reflected the character of the prevailing winds from that direction. Zephyrus, the west wind, for example, was a good wind, a bringer of fresh Spring air and life. Boreas, a north wind, was frequently depicted as an old and sinister fellow, who brought death with his cold breath.

Note that the Ptolemy-Germanus map covers only slightly more than one quarter of the surface of the Earth-180 degrees longitude and roughly 90 degrees latitude. In his text, Ptolemy called this area the habitable world (oikoumene or Ecumene). This did not mean that there was nothing beyond that world. Many ancients believed that another world-the Antipodes-existed on the other side of the world, south of the Equator, but it was inaccessible to inhabitants of northern climes. Ptolemy and the Greeks also thought that there was a great encircling world ocean that was prohibitively large. But to Renaissance Europeans, who were more familiar with more distant parts of Asia and Africa than Ptolemy, the Germanus-Ptolemy world map suggested the possibility of moving beyond Ptolemy's closed and limited world.

We know that Christopher Columbus's goal in 1492 was to pioneer a trade route to East Asia by sailing west. We also know that Columbus owned and annotated a copy of the 1490 Rome edition of the Geographia, which was also edited by Germanus. We have before us then one of the most influential world maps that Columbus saw in the years he was planning his great, but accidental voyage of discovery. Unfortunately for Columbus, Ptolemy underestimated the size of the Earth by one sixth. Columbus's contemporaries thought the Eurasian landmass was as much as 230 degrees wide, placing Japan 50-70 degrees west of the Iberian coast (it is actually about 210 west). Japan does indeed appear to be roughly 60-70 degrees west of the European coast in a globe made by Martin Behaim in Nuremberg in 1492 (while Columbus was still at sea). As a result Columbus calculated that Japan and East Asia would be found roughly where the West Indies are. This explains why Columbus died still believing that he had not discovered a New World but achieved his goal of establishing a short route between the opposite ends of the old one.

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Notes on the Supplemental Map
Gregorio Dati, World "T-in-O" map based on a model by Isidore of Seville. In La Spera (Florence, ca. 1425).

Contrary to a commonly held belief, many medieval Europeans understood the world to be round-or, rather, spherical. The sphericity of the earth was certainly common knowledge among the wealthier and learned classes of late medieval Florence, Italy, where this highly simplified map of the world was drawn, perhaps around 1425. The map is one of several maps and diagrams of the Universe that appeared in La Spera ("The Sphere"), a primer in the rudiments astronomy and geography written by a Florentine silk merchant named Gregorio Dati (1362-1435). As the title indicates, La Spera describes the sphere that encompasses all of Creation as late medieval scholars professed it to be. This was a rather small Universe by our standards, with the Earth at the center, surrounded by a series of twelve concentric, rotating spheres. La Spera begins with a description of the outermost spheres, which were thought to hold the containing the stars, the planets, the Sun, and the Moon. Diagrams (or maps, if you will) of the Universe appear at the margins of most of the pages. These diagrams explain, for example, the causes of eclipses and the origin of the seasons and climates. Next come descriptions of the four spheres below the one holding the Moon, which corresponded to what were thought to be the four elements of all matter: fire, air, water, and, in the center of all Creation, earth. The book closes with a survey of the geography of the Mediterranean parts of Asia and Africa.

La Spera thus combines the modern sciences of astronomy and geography, with a generous measure admixture of cosmology. In the parlance of its time, this kind of book was sometimes called a "cosmography," an account of the Cosmos. Geography was regarded as a subset of cosmography, concerned primarily with the measurement and description of the Earth. Over 200 manuscript (hand-written) copies of the La Spera survive in libraries throughout Europe and the Americas, so it must have been widely read. It was written in Italian verse, suggesting that it was intended as a pedagogic text; it was common at the time to prepare textbooks in verse to aid memorization of the information they contained.

This simple world map from La Spera belongs to a class of common medieval representations of the Earth known as "T-in-O" maps, because their schematic division of the known world into three continents looks like a capital "T" inside an "O." A seventh-century scholar, Isidore of Seville, is credited with originating this type of mappamundi ("world map"). The map bears little resemblance to geographical reality, yet its simple delineations have deep religious and cosmological significance. The stem of the "T" corresponds to the Mediterranean Sea, its southern (right) arm to the Nile or Red Sea, and its northern (left) arm to the Black Sea. Inside these rough boundaries are Asia (at the top of the map), Africa (at lower left), and Europe (at lower right). Some versions of the T-in-O map include the names of each of the three sons of Noah who were supposed to have fathered the races of men that settled each of the continents after the Biblical Flood: Shem (Asia), Ham (Africa), and Japheth (Europe). In many traditional societies, one or more of the four cardinal directions had religious significance. In medieval European Christianity, East was the location of Jerusalem, the Holy Land, and the Garden of Eden. Medieval mappamundi therefore frequently were oriented with East (in Latin, oriens) at the top. The entire land surface is encircled by a world Ocean, which corresponds to the first of the spheres encompassing the earthly one.

The geographical inaccuracies of this map are obvious to readers who troubled to compare them with the more detailed ones of the Mediterranean region that appear later in La Spera. But the purpose of these maps, and of the others like them that have survived from medieval times, was not to teach geography in detail. Rather, the intent was to provide a broad framework that explained how the geographical world fit into an orderly cosmology, in which every celestial body and every element had its place in divine Creation.