Have you ever listened to a fictional story being read aloud and envisioned the characters moving around in your mind’s eye, as though within your own, interior theater? If you have, then you have experienced what medieval intellectual culture considered to be a form of memory. This kind of creative mental visualization—what those of us in the 21st century might call ‘using our imagination’—was once thought to be a kind of memory.

Many of us have a distinctive doodle. We can recognize our former school notebooks from the familiar designs that repeat in various combinations on the corners of pages. Some of these drawn figures may still inadvertently appear on a memo pad when we find ourselves on a lengthy telephone call. The connotation of the word “doodle” implies that the penwork lacks intentionality, and therefore fifteenth-century scribes in the Northern Netherlands cannot be said to have “doodled” in the borders of their manuscripts. Nevertheless, the effect of their labors on paper and parchment is remarkably similar to some of our finer memo pad masterpieces.

“Just use some common sense” is not a phrase that Gregor Reisch (1467-1525) would have leveled against any of his students when the first edition of his textbook, Margarita Philosophica, was printed in 1503. By all accounts, sixteenth-century students were just as rambunctious as contemporary adolescents, so it is not that the Carthusian Prior of Freiburg may have been without occasion. However, in 1503, “common sense” did not refer to a person’s ability to reason. Dogs, sheep, and other animals had “common sense” or, in Latin, a sensus communis. This particular faculty of the mind was thought to be the single internal entry point for all external sensations: sight, hearing, smell, taste, and touch.