Difficillima et Ardua: theory and practice in treatises on the abacus, 950–1150

The abacus is often regarded as a comparatively simple instrument of calculation. Yet the scholars of the tenth to twelfth centuries who wrote the practical manuals on the use of the abacus often went to some lengths to relate their teaching to the work of their contemporaries in the other artes, and to provide theoretical explanations for the principles involved. They sought to elevate the study of the abacus to the status enjoyed by the other arts. This paper attempts to examine the range of their treatment and the limitations imposed on their efforts by their subject-matter.