Name: Sacrobosco’s ‘De Sphaera Mundi’
Author: Johannes Sacrobosco

The Sunderland Collection

There were two-hundred editions of Sacrobosco’s ‘Sphere of the World’ printed between between 1472 and 1673, and fifty-six editions of Peurbach’s, ‘New Theories of the Planets’ published until 1653. ‘M. Sebastiani Gleyss ex purgstall austriaci sum 1515’, inscription on title. 

The first work, Sacrobosco’s ‘Sphere of the World’, heavily endorses the geocentric model of the cosmos presented in Claudius Ptolemy's 'Almagest'. It describes the structure and motions of the planets, especially the motions of the Sun, Moon and fixed stars. The work also provides dimensions of the Earth and the latitudes of different climatic zones. This compendium is packed with diagrammatic images that complement the astronomical descriptions in the text, seven of which are coloured. One illustration depicts the ‘theory of the lunar eclipse’, followed by the ‘theory of the solar eclipse’; both accompany tracts of text in the third work in the book, Peurbach’s, ‘New Theories of the Planets’, some editions of which have up to twenty-nine diagrams.

Written in simple Latin, this book compiles three early scientific works into a single volume that would have been invaluable to fifteenth-century astronomy students.

The first work in this book is an edition of Johannes de Sacrobosco’s ‘Sphere of the World’ (‘De Sphaera Mundi’), which was originally written in around 1230. It explains the structure and motions of the planets, provides the dimensions of the Earth, and the latitudes of different climatic zones. The ‘Sphere of the World’ was one of the the most popular astronomy textbooks in Medieval and Renaissance Europe: between 1472 and 1673, more than two-hundred editions were published, ensuring its status as the standard astronomical textbook across Europe for nearly four centuries.

The second work is Johannes Regiomantanus’s, ‘Dispute against [the work of] Cermonensia’ (‘Disputationes contra Cremonensia’) - likely Gerard of Cremona, a twelfth-century astronomer who provided an early translation of Ptolemy’s ‘Almagest’ from Arabic into Latin.

The third book is Georg von Peurbach’s, ‘New Theories of the Planets’ (‘Theoricae Novae Planetarum’), a work that gradually replaced Sacrobosco’s ‘Sphere of the World’, and features updates to the theories based on the work of Gerard of Cremona. Fifty-six editions of Peurbach’s work were published until 1653.

This book is packed with diagrams that help explain the theories promoted by these astronomers. The work also includes a full-page coloured frontispiece depicting ‘Astronomia’ enthroned, flanked by ‘Urania’ on the left and Ptolemy on the right. These works provide an important in understanding how medieval authors influenced Renaissance astronomy, and a timeline to tracing the evolution of astronomical theories.

Johannes Sacrobosco (c.1200–c.1250), a teacher at the University of Paris, wrote ‘The Sphere of the World’ (‘De Sphaera Mundi’) around 1230 as an introductory astronomy textbook for his students. It went on to become the most popular and widely used astronomy text in Europe, remaining influential until the end of the seventeenth century.

Also included in this compendium are works by two leading fifteenth-century astronomers: Johannes Regiomantanus’ ‘Dispute against [the work of] Cermonensia’ (‘Disputationes contra Cremonensia’) and Georg von Peurbach’s, ‘New Theories of the Planets’ (‘Theoricae Novae Planetarum’) which were both first published - by Regiomantanus - less than a quarter-century before this compendium was produced. Regiomontanus, a pupil of Peurbach, collaborated with his teacher to revise Gerard of Cremona’s Latin translation of Claudius Ptolemy’s ‘Almagest’ (1496). Their updated version was commissioned by Cardinal Bessarion (1403–1472) and published at the end of the fifteenth century.

Frontispiece

Armillary Sphere

Geometric diagrams

Diagram of the 'heavenly' and earthly spheres

Illustrations of a spherical Earth

Zodiac diagram

Diagram of the Earth's climatic zones

Diagrams of the movement of celestial bodies

Diagram of the movement of celestial bodies

Geometric diagram

Diagrams of the Sun and Moon

Lunar diagrams

The work features a glorious full-page woodcut on the reverse of title-leaf showing ‘Astronomia’ enthroned. She is flanked by ‘Urania’, the muse of Astronomia and goddess of celestial knowledge, to her left, and polymath Claudius Ptolemy on the right.