Of all misconceptions about the Middle Ages, one of the most persistent and erroneous is the idea that people before Columbus thought the world was flat—a myth invented wholesale in 1828 by American novelist Washington Irving. Even medieval schoolchildren began their study of cosmology and natural philosophy with the round earth, as we see in La sfera (The Globe), a curious vernacular textbook written circa 1425 in ottava rima by the Florentine merchant Gregorio Dati. The present obscurity of Dati’s treatise belies its bestseller status in its own time, as demonstrated by its survival in approximately 165 manuscripts and 18 printed editions all predating the year 1500.

Dati’s treatise provides a concise introduction to medieval cosmology, science, geography, and navigation: all the basic information a young Florentine merchant-in-training would need to understand the natural phenomena affecting travel and trade around the turn of the fifteenth century. Yet labeling La sfera a “school text” does not explain the enormous number of surviving manuscripts, nor the vast diversity in their appearance and production values. While some are utilitarian owner-produced manuscripts, many Sfera manuscripts contain luxuriously illustrated sets of cosmological diagrams and maps—particularly in book 4 of the treatise, which provides a port-by-port itinerary of the Mediterranean coastline from West Africa to the Black Sea. Dati’s poem discusses the voyage along the Canary Islands and the coast of west Africa, the cold waters of the north pole, the rivers of Central Asia, and the dangerous fauna of the African desert. La sfera’s global perspective is also a powerful witness to the eastward orientation of most European ventures of the time—an attitude grounded in the commerce as well as the theology of the period. In this way La sfera crystallizes a crucial transitional moment of the European worldview somewhere between the invention of the dry magnetic compass around 1300 and the traditional “Age of Exploration” beginning at the end of the fifteenth century. Dati’s treatise is unique in how it spans the practical world of cartography and the more impressionistic world of travel literature (such as the works of Marco Polo or Ibn Battutah). Further, its integration of medieval navigational charts or portolans with the more classicizing tradition of Claudius Ptolemy’s Cosmographia (translated in Florence, during Dati’s lifetime) gives Dati’s work a major and hitherto unappreciated role in the history of cartography.

Dati’s Sfera is therefore long overdue for a modern critical edition that will make it accessible to scholars of the Mediterranean world, the history of cartography, and the history of Italy at the threshold between the Middle Ages and the Renaissance. Yet before the online cataloging and manuscript digitization efforts of the last twenty years, it would have been impossible to establish a good picture of the size and diversity of the large Sfera corpus. While about half of the extant manuscripts are still in Florentine libraries, the rest are dispersed across the globe. As a result, most of the modern scholarship on La sfera has tended to rely on one or only a few manuscripts at a time, and until the creation of the Sfera Project (http://www.sferaproject.org) no one has tried to assess the size and scope of the full corpus.

The Sfera Project is a collaborative effort to transcribe, translate, and create a digital edition for Dati’s Sfera. The digital medium can support and showcase the multimodality of Dati’s original treatise—which combines texts, images, and maps—in ways that a traditional print edition cannot. Along with the Italian text and English translation, our edition will incorporate an editorial introduction, hyperlinked explanatory notes, annotated IIIF manuscript images from a variety of sources, and a georeferenced ArcGIS gazetteer locating the toponyms in Dati’s work. True to the project’s crowd-sourced roots (the 2020 #lasferachallenge), our digital edition is also designed to be extensible, in order to incorporate additional manuscript transcriptions as they are produced either by our pre-existing community of Sfera scholars or by new users who join the scholarly effort.

The La Sfera Project will therefore create a multifunction, multimedia interface that will present Dati’s integrated world of cosmology, geography, and cartography using visual, textual, and spatial data. While researchers are increasingly interested in understanding how geographical knowledge and cartography developed in and around the Mediterranean in the 14th and 15th centuries, few reference resources exist which summarize that knowledge or help scholars identify toponym variants. The large Sfera manuscript corpus provides a rich body of evidence for spatial analysis but also presents numerous challenges. This paper will explain the Sfera Project team’s analysis and choices with regard to such questions as: the use of GIS and linked open data to locate and identify medieval places in modern terms; digital techniques for documenting vague, anachronistic, or imaginary places; and efforts to balance usability with respect for each manuscript’s idiosyncrasies of labeling, orthography, and visual representation; and database and interface design, as we attempt to reproduce and make legible La sfera’s complex combination of text, maps, and images.