Johannes de Sacrobosco

Who was Johannes de Sacrobosco?

Johannes de Sacrobosco, also written Ioannis de Sacro Bosco was a scholar, monk, and astronomer who was a teacher at the University of Paris. He is notable for three things. First, he wrote a short introduction to the Hindu-Arabic numeral system which became the most widely read introduction to that subject in the later medieval centuries. Second, he wrote a short astronomy textbook, Tractatus de Sphaera, which was widely read and influential in Europe during the later medieval centuries as an introduction to astronomy. Third, in his longest and most original book, written more than three centuries before the introduction of the Gregorian calendar, Sacrobosco correctly described the defects of the then-used Julian calendar and with a pretty good degree of precision he recommended what was essentially the Gregorian calendar.

Very little is known about the education and biography of Sacrobosco. For one thing, his year of death has been guessed at 1236, 1244 and 1256, each with plausibility and each with lack of adequate evidence.