Medieval World: Quadrivium > Page 4
JOHANNES DE SACROBOSCO, CA. 1195–1256
Algorismus
Manuscript book on paper Germany, mid 15th century
Plimpton MS 184
Here stands Astronomy, in flowing red robes holding a representation of the earth divided into zones (the red lines) with the courses of the moon and the sun (the green lines). The scroll contains one line of Latin: it’s the first of an 11-line poem in which each of the seven liberal arts introduces herself, followed by lines for Philosophy, Nature, the Trinity and Wisdom. Astronomy continues here in German: “I, Astronomy, can know above all others what the course the planets run.” The owner, and probably producer, of the book proudly names himself on this page, Hainrich Muglinck, and elsewhere he declares himself the “astronomer of astronomers.”
Gift of George Arthur Plimpton
JOHANNES DE SACROBOSCO, CA. 1195 – CA. 1256
De sphaera mundi
Manuscript book on paper and parchment
Low Countries, end of the 15th century
Plimpton MS 183
Johannes de Sacrobosco, or John of Holywood, was educated at Oxford, and taught at the University of Paris beginning in the 1220s. He produced his Tractatus de sphaera, his most important work, by about 1230. It became the authoritative astronomy text for the following four centuries, disproving the common idea that the medieval world thought that the earth was flat.
Gift of George Arthur Plimpton
PTOLEMY, 2ND CENTURY
Quadripartitum
Venice: Erhard Ratdolt, January 15, 1484
Incunabula Goff P-1088
Erhard Ratdolt also produced this first edition of Ptolemy’s work on astronomy and astrology, in four books (better known today as the Tetrabiblos), in 1484. It is considered the most important surviving text of Greek astrology.
Gift of George Arthur Plimpton
ANIANUS
Computus cum commento
[Basel: Lienhart Ysenhut, circa 1490]
Incunabula Goff A-734 (Plimpton 529 1490)
Computus is the art of ascertaining time by the course of the sun and the moon. While historical and theoretical studies of the subject did exist, much computistical work focused on the fundamental question of the date of Easter. Easter is observed on the first Sunday after the full moon that happens on or immediately after the spring equinox, itself taken as occurring on 21 March. This requires concordance among three time-measuring systems: the phase of the moon, the course of the sun and the day of the week. As David Eugene Smith wrote in his History of Mathematics, the first printed work on Computus was this text by Anianus, appearing in 1488 in Strasburg. It and subsequent editions contained the first printing, in Latin, of the familiar rime “Thirty days hath September.”
Gift of George Arthur Plimpton