Liberal Arts and Education
BPL 191 BD (Germany, 1100-1150): Hrabanus Maurus, De Computo (On Calculation), parchment, 26 fols., 263 x 194 mm, 1 col., 38 lines.

Young children today often use their fingers to count. As they get older, they can solve mathematical problems without their fingers, often aided by the calculators on their cellphones. However, during the Middle Ages finger counting was used by even the most experienced mathematicians. People were able to count to a thousand, just by using their two hands. The numbers 1-99 were counted on the left hand, while the numbers 100-9999 were counted on the right. Fol. 4r in this manuscript depicts an illustration of how to count on your fingers according to the method used at the time.

The illustration is part of Hrabanus Maurus’ De computo (On Calculation). The text is written as a dialog between a teacher and student who ask each other questions about the computus system (see also BPL 154). Maurus’ text on calculation was frequently copied in schoolbooks, owing to its accessible way of presenting information. Like the drawings on finger counting, these tools were probably meant to aid1 the students with their own calculations.

(Gumbert, 2009, p. 92) (Scheller, 1970, pp. f.4r-5v) (Gerritsen, 2007, pp. 24-30)


  1. Users often modified the manuscript post-production, bringing it even more in tune with their needs. How did the readers of this manuscript interact with the texts? Clue: take a look at the margins and the flyleaves.
  2. Producing manuscripts was expensive. Some readers preferred to own expensive books, for example for conspicuous consumption, while others preferred to economize and cut costs wherever possible. Observing such features as materials (parchment, paper, binding), preparation of the page (the care with which the page was designed), and the execution of the letter forms, speculate what the intentions of the first reader will have been: to economize or not?


  1. Gumbert, J. P. (2009). Illustrated Inventory of Medieval Manuscripts in Latin script in the Netherlands. Verloren.
  2. Scheller, R. W. (1970). Kunst, geschiedenis, rekenen. Menno Hertzberger.
  3. Gerritsen, W. P. (2007). Europa’s leerschool: de zeven vrije kunsten in de Middeleeuwen. Een rondgang langs Leidse handschriften. Primavera Pers.