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Mathematical Treasure: 13th-Century Computus of Anianus

Frank J. Swetz (The Pennsylvania State University)

Computus cum commento was published in 1488, together with Johannes Sacrobosco’s (ca. 1195-1256) De algorithmus, in one volume. For images of a manuscript copy of Sacrobosco's Algorismus, or Tractatus de arte numerandi, see Mathematical Treasure: Sacrobosco's Algorismus.

The title page of the Computus cum commento is shown here:

Title page of Computus cum commento by Anianus, 1488

While the author of this computus is given as one “Anianus,” the exact identity of this individual remains in question. D. E. Smith identified him as a 13th century French monk and several sources have accepted this conjecture and placed him in the period ca. 1250-1300. Since a computus was a Church mathematical manual devoted to the determination of the date of Easter, the association with a monk is plausible.

The first page of the text contains an illustration of peasants looking to heaven questioningly. An angel appears to be offering them information.

First page of Computus cum commento by Anianus, 1488

In the instructions, Anianus employed hands as references.

Images of labeled hands from Computus cum commento by Anianus, 1488

The images above are provided courtesy of Columbia University Libraries.

Index to Mathematical Treasures

Frank J. Swetz (The Pennsylvania State University), "Mathematical Treasure: 13th-Century Computus of Anianus," Convergence (June 2018)