Liberal Arts and Education
BPL 191 E (Germany and Italy, 1100-1200): Reinherus, Computus Emendatus (Corrected Computation), parchment, 180 fols., various sizes, various cols., various lines.

The date on which Easter is celebrated depends on the phase of the moon in relation to the Spring Equinox, and therefore varies year-to-year. Determining the date of Easter required profound knowledge on astronomy, especially the lunar calendar. In 1171 Reinherus of Paderborn (c. 1140-c. 1190) published the Computus emendatus (Corrected Computation) in which he proposed a corrected table with the Easter dates, as he had determined that the currently-accepted dates were flawed. Paderborn claimed, for example, that Easter was celebrated three days too late in 1171.

The Computus emendatus is one of the eight texts in this manuscript. It also contains excerpts on grammar and astronomy, glosses on the Bible, and letters from Ivo of Chartres. The different texts were bound together some time later, resulting in a variety of lay-outs throughout the manuscript. In the margins of the first part of this manuscript (fols. 1r - 60v) you can see unusual marks, known as nota bene1 markings, on almost every leaf. If you look closely you can see that each drawing is a monogram of the letters n, o, t, and a. Nota bene markings vary in appearance from page to page.

(Gumbert, 2009, pp. 90-92) (Gerritsen, 2007, pp. 34-37)


  1. Mistakes are made in a split-second. Even scribes who carefully copied their text, a few words at the time, would ultimately make mistakes. Can you give three examples in this manuscript where a part of the text was corrected? Note how the mistakes were corrected.
  2. Some manuscripts were made for institutional use, for example for a monastery, a nunnery, or a school. Others were made for one specific reader, who may even have made the book for him- or herself. While it is not easy to deduce whether the scribe made the manuscript for a community or a specific individual (or even for personal use), material features can sometimes provide clues to this end. Study this manuscript in search for such clues. Look for ownership inscriptions (often in the front or back of the book), the number of different individuals who added information into the margins (the script may help you here), and the number of entries added by these individuals. If you had to speculate, for what scenario would you opt and why: community or individual use?


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