Imago mundi

Pierre d’Ailly’s Imago mundi was written in 1410; this printed edition adds several related treatises and was published in the 1480s. Christopher Columbus used and annotated it when he was developing his plan to reach Asia by sailing west. D’Ailly (1351-1420) wrote the first thirteen of eighteen treatises contained within the Imago mundi, with the last five being written by Jean Gerson (1363-1429). Columbus added almost a thousand annotations to his copy. D’Ailly, like Gerson, was a bishop; his Imago mundi was written in part to study astrological and religious cosmography.  

The Imago mundi is made up of treatises intended to bring all geographical knowledge into a single manuscript. Manuscripts like this aimed to place the Earth within the universe, both physically (through celestial maps) and spiritually, with maps that tie elements to geography. These connections could show how God had created the world, as everything was tied together and connected. The Imago mundi also recorded estimates of the size of the earth and the Eurasian continent which allowed Columbus to believe that the distance from Portugal to India was much shorter than it was. 

The Imago mundi contains seven pages of printed maps with added color, mostly focusing on celestial and zonal maps. These maps tend to not focus on landmasses, but rather how the Earth functions within a broader universe. The earth is split into five sections in the zone map. The uppermost and lowermost parts of the north-oriented map represent uninhabitable zones, due to temperatures being too low. The central section, containing the equator, was thought to also be uninhabitable due to temperatures being too high. The two habitable zones, in this case north of the Tropic of Cancer and south of the Tropic of Capricorn, are the spaces where humans can settle. 

The Imago mundi was written before d’Ailly had access to Ptolemy’s “Geography”, and d’Ailly later published more works that supplemented and complemented his Imago mundi with the information he had gained. He was very interested in Ptolemy’s ideas of climate zones, as they did not fully agree with his own; in particular, the habitable zones did not match fully. His later work, “Compendium,” acts as a summary of Ptolemy’s “Geography”, but with d’Ailly’s views superimposed as well. (Eleanor Lewin, 2027)

Cosgrove, Denis E. “Images of Renaissance Cartography 1450-1650.” In The History of Cartography, vol. 3, part 1, Images of Renaissance Cosmography, 1450–1650, ed. David Woodward. 55-98 Chicago: University of Chicago Press, 2007.

Edson, Evelyn. “Chapter 3: The Nature of Things.” Mapping Time and Space : How Medieval Mapmakers Viewed Their World. London: British Library, 1999.

Gautier Dalché, Patrick. “The Reception of Ptolemy’s Geography.” In The History of Cartography, vol. 3, part 1, Cartography in the European Renaissance, ed. David Woodward. 285-364 Chicago: University of Chicago Press, 2007.

Smoller, Laura Ackerman. History, prophecy, and the stars: the Christian astrology of Pierre d’Ailly 1350-1420. Princeton, N.J.: Princeton University Press, 1994.

Wey Gómez, Nicolás. The Tropics of Empire: Why Columbus Sailed South to the Indies. Cambridge: MIT Press, 2008.

Woodward, David. “Medieval Mappaemundi.” In The History of Cartography, vol. 1, part 3, Cartography in Medieval Europe and the Mediterranean, ed. J.B. Harley and David Woodward. 286-370 Chicago: University of Chicago Press, 1987.