The Imago Mundi (“Image of the World”), written in 1410 by the French bishop and scholar Pierre d’Ailly (1351-1420) is one of the most important geographical works of the late Middle Ages. Focused on geography and cosmography, this encyclopedic work was one of the most consulted treatises of the time, and was used by Christopher Columbus to develop his ideas about the viability of navigating the Atlantic to reach the Indies.
In fact, this specific copy of Imago Mundi was one of the most consulted books by Columbus, whose abundant annotations are clearly visible in the margins of the pages. Thus, this book was a very important item in the preparation of the voyages that resulted in the discovery of the New World.
The Most Important Book in Columbus’ Library
This exemplar of Pierre d’Ailly’s Imago Mundi was printed in Leuven by Johannes of Westfalia in 1483. It measures 28 x 21 cm, and includes abundant diagrams and drawings that serve as graphical evidence of d’Ailly’s theories. These theories were based on authors like Aristotle, Ptolemy, Pliny the Elder, the Church Fathers and Arab writers like Averroes among others.
Nevertheless, the whole book is not the work of d’Ailly. It is composed of eighteen treatises, of which the first thirteen were written by d’Ailly and the last five by his disciple Jean Gerson (1363-1429), philosopher and chancellor of Paris (please find list below).
The exemplar is heavily annotated by Columbus (there are 898 annotations according to scholars), which indicates that he studied d’Ailly’s work thoroughly. The annotations emphasize the ideas and theories that supported Columbus’ project. Thus, this exemplar of Pierre d’Ailly’s Imago Mundi, held in the Biblioteca Colombina in Seville, is one of the most important items which preceded the discovery of America.
The Books used by Columbus to Demonstrate his Theories
Columbus had to defend himself from the skeptics who doubted the possibility of reaching the Indies by crossing the Atlantic. Thus, he collected several works to prove his geographical and cosmographical theories.
Some of those works were Eneas Silvio Piccolomini’s Historia rerum ubique gestarum (1477), Marco Polo’s De consuetudinibus et conditionibus regionum orientalium (1485), Pliny’s Natural History translated by Landino (1489), Plutarch’s Vitae (1491) and Pierre d’Ailly’s Imago Mundi (1483), which is the book discussed here.
These exemplars were very important in Columbus’ library, which passed on to his son Hernando after the Admiral’s death in 1506. This collection was the seed of the Biblioteca Colombina in Seville, one of the most important libraries regarding the discovery of America.
List of Treatises Included in the Imago Mundi
By Pierre d’Ailly:
1. Imago mundi, ff. 1r-39r.
2. Epilogue on the Mappae Mundi (Epilogus mappae mundi), ff. 39r-43v.
3. Treatise About the Laws and the Cults (Tractatus de legibus et sectis contra superstitiosos astronomos), ff. 44r-57v.
4. About the Correction of the Calendar (Super Kalendarii correctionem), ff. 57v-63v.
5. About the True Lunar Cycle (Tractatus de vero cyclo lunari), ff. 63v-68r.
6. Compendium of Cosmography I (Compendium cosmographiae I), ff. 68r-83r.
7. Compendium of Cosmography II (Compendium cosmographiae II), ff. 83v-89v.
8. Twenty Propositions About the Concord of Astronomic Truth With Theology (Vigintiloquium de concordia astronomicae veritatis cum theologia), ff. 90r-103r.
9. Treatise About the Concordance of Astronomic Truth With Historical Narration (Tractatus de concordantia astronomicae veritatis et narrationis historicae), ff. 103r-121r.
10. Explanation About the Concordance of Astronomy With Theology and Historical Truth (Elucidarium astronomicae concordiae cum theologica et historica veritate), ff. 121-143r.
11. Apologetic Defense of the Astronomical Truth I (Apologetica defensio astronomicae veritatis I), ff. 143r-145v.
12. Apologetic Defense of the Astronomical Truth II (Apologetica defensio astronomicae veritatis II), ff. 145v-148r.
13. Treatise About the Agreement of Disagreeing Astronomers (Tractatus de concordia discordantium astronomorum), ff. 148r-157v.
By Jean Gerson:
14. Thirty Propositions of Theologized Astrology (Trigilogium astrologiae theologisatae), ff. 157v-163v.
15. Opuscule of Theologized Astrology (Opusculum astrologiae theologisatae), ff. 163v-165v.
16. Opuscule Against the Superstitious Observance of Days (Opusculum contra supersticiosam dierum observationem), ff. 166r-167v.
17. Against the Doctrine of a Physician From Montpellier Who Engraved in a Coin the Figure of a Lion for the Recovery of the Kidneys (Adversus doctrinam cuiusdam medici Monte Pessulano sculpentis in numismate figuram leonis cum certis caracteribus pro curatione renum), ff. 167v-169r.
18. Opuscule Against the Superstitious Observers of Days (Opusculum contra supersticiosos dierum observatores), ff. 169r-170r.