[this is the third segment of a post started here (part 1), and continued here (part 2)]
Mind maps were the most popular type of diagram. By the time universities emerged towards the end of the 12th century, diagrams had become the main tool for organising information and knowledge. A way to understand the human soul (anima) was through complex diagrams linking Aristotelian theory with modern (i.e. medieval) ideas.
A pie chart of the human soul, with diagrams of human faculties, fields of knowledge and types of emotions, Harley MS 658, f. 41r.
A complex zoomorphic diagram connecting elements of ethics, kinship, law and theology, Cotton Roll XIV 12, membrane 37.
Diagrams offered an overview of various fields of knowledge, like language, rhetoric, logic, maths, astronomy or music. They fostered abstraction and the view from above, which accustoms the human mind to look at things lying beyond the field of vision.
While it was common to represent the constellations of the zodiac in manuscript, it was quite rare to depict all the constellations of the Northern Hemisphere in one diagram, like in this 11th-century manuscript from Canterbury, Harley MS 647, f. 21v.
The development of cartography tracks the evolution of diagrams closely. Admittedly, maps already existed in the ancient world, but the science of mapmaking emerged in the medieval period. Maps are views from above, using an abstract representation to model a field lying beyond the field of vision. While a diagram of the universe, like in Harley MS 647 (see image above), projects a theoretical model independent of empirical observation (notwithstanding occasional medieval stargazing), a nautical map is an abstraction derived from experience.
This nautical chart of the Atlantic coast uses coastal outlines and rhumb lines for sailing navigation. The history of modern mapmaking begins with portolan maps like this one made in Venice around 1331, Additional MS 27376, ff. 180v-181r
