Volume XII · Winter 1957 · Number 2
A Fifteenth-Century Text on Astronomy
--JOHN R. RUSSELL
 
 

Fifteenth-century books on science are not easily acquired today, so the Library is especially fortunate in having recently obtained a copy of the Sphaera mundi by Johannes de Sacrobosco, printed at Venice by Erhard Ratdolt in 1482. This purchase was made from the Hiram Olsan Fund, a fund given in memory of Dr. and Mrs. Hiram Olsan and used for the purchase of rare books for the Treasure Room. This interesting addition to the collection is the fifteenth incunabulum purchased from the Hiram Olsan Fund. Earlier acquisitions have been described in the issues of this Bulletin dated "Winter 1948" and "Spring 1951."

Although this work on astronomy is listed in bibliographies under the name of Sacrobosco, the author of theSphaera mundi, his text occupies only about a fourth of the volume. Two other works on astronomy complete the volume, making it a compendium on astronomy that doubtless served many university students as a textbook. Since Sacrobosco's treatise comes first in the volume, his work has the position of greatest importance, and so the book is always referred to under his name.

Johannes de Sacrobosco, or John of Holywood, or Halifax, probably was an Englishman, although even his nationality is uncertain. The fact that he wrote disparagingly of the English climate has, led some to believe that he could not have been an Englishman. He lived at the end of the twelfth century and the beginning of the thirteenth century, and apparently spent most of his lifetime in Paris, where he was a student and teacher of mathematics and astronomy at the university. His extant writings are few in number, consisting of textbooks on astronomy and mathematics.

The Tractatus de sphaera, or Sphaera mundi, was written quite early in the thirteenth century, the exact date being unknown. Its popularity as a text is shown by the large number of manuscript copies made in the thirteenth to fifteenth centuries that still exist, and by the many printed editions of it that appeared in the fifteenth to seventeenth centuries. In the fifteenth century alone there were at least twenty-four printed editions published in Ferrara, Venice, Bologna, Leipzig, Cologne, and Paris, the earliest having been printed at Ferrara in 1472.

In the writing of his book on astronomy Sacrobosco drew heavily on the works of others. He used the writings of Macrobius and the Almagest of Ptolemy, and he also drew on the Arabian writers, especially Alfraganus. However, he did not follow his predecessors slavishly, and the great popularity of his book was doubtless due in part to the superior organization that Sacrobosco gave to the material and the clarity with which he presented it. He did much more than reproduce the ideas of one or two earlier writers. He studied all the sources that were available to him and chose the material that would be most useful to university students. Lynn Thorndike describes his book as "the highly finished production of Sacrobosco, which from both literary and pedagogical viewpoints is a finely polished little gem."

Sacrobosco showed in the Sphaera mundi his knowledge of literary classics as well as his grasp of the science of astronomy. He quoted from a number of the classic writers including Virgil, Ovid, and Lucan, in many instances relating quotations from classical poetry to his astronomical descriptions. Thorndike says, "Apparently, Sacrobosco wrote at just the right time to make a skilful combination of and compromise between, the old literary astronomy of the early Middle Ages and the new scientific astronomy of the twelfth-century translators from the Arabic. He welded together Macrobius and Ptolemy and frosted it over with Alfraganus, and his book stayed in style for five centuries."

The second text in this volume is the Disputationes contra Cremonensia by Johann Müller, known as Regiomontanus (1436-1476). This treatise had as its purpose the correction of some of the work of the twelfth-century writer Gerardus Cremonensis, who had learned Arabic in Toledo and devoted the remainder of his life to making Latin translations from the Arabic, including Alfraganus's text on astronomy. His Latin translation of Ptolemy's Almagest was widely used by students of astronomy.

Regiomontanus, with the help of his wealthy patron, Bernhard Walther of Nuremberg, equipped the first astronomical observatory in Europe, and established a printing press in Walther's house on which several scientific texts were printed, including the first edition of the Disputationes contra Cremonensia (c. 1475). He also printed, probably about 1474, the Theoricae novae planetarum, written by his teacher and colleague George Purbach (1423-1461), which is the third and last work in the book being described. In this work Purbach gave a rather detailed account of the theory of the planets, a subject not covered by Sacrobosco, and pointed out "the discrepancy between the views of Aristotle and those of Ptolemy."

The fact that the second and third parts of this recently acquired book on astronomy were first printed at Nuremberg by Regiomontanus himself naturally leads us to a consideration of the printer of this book, Erhard Ratdolt, for he could have been working for Regiomontanus in his printing shop at the time these two astronomical texts were being printed. It is known that he left his native city of Augsburg about 1474, and there is no record of his activities until 1476, when he began printing with two associates in Venice. Because of Ratdolt's preference for printing scientific works, including those by Regiomontanus, some have conjectured that the two years for which there is no record were actually spent with Regiomontanus in Nuremberg.

While Ratdolt printed many scientific works, he also did editions of liturgical works, history, and the classics. The first book to be issued from the press established by Ratdolt and his two associates in Venice was theKalendarium of Regiomontanus, which they published in 1476, three years after the first edition had been printed by Regiomontanus himself. This new edition was a great improvement over the earlier one, and has the distinction of being the first printed book to have an ornamental title page. Ratdolt frequently used ornamental borders and initial letters in his printing, and he soon became well known for the beautiful books he produced-so well known that he eventually was induced to return to his native city of Augsburg to establish a press there, which he did in 1486. From 1476 until the time he left Venice he had been the sole proprietor of his printing business and had printed some thirty books, including the one we have just acquired. His career as a printer at Augsburg lasted for more than forty years, during which he produced a notable group of books, differing considerably in style from the work of other German printers because of his superior craftsmanship and because of the superiority of the woodcut borders, initials, and illustrations that he brought back from Italy.

The Sphaera mundi which Ratdolt printed in 1482 serves as an excellent example of the artistry of his printing. While it does not make use of ornamental borders, it does have many attractive initial letters done in the "sgraffito manner," that is, with white ornaments on a black background. It also has numerous astronomical diagrams clearly reproduced and well placed in the text. Ratdolt was the first printer to use colored astronomical diagrams, and in the Sphaera mundi of 1482 these diagrams were colored by hand. In later issues from his press colored diagrams were produced by printing in color.

With this latest addition to its rare book collection the Library now has six examples of the work of Erhard Ratdolt, four of them from the time when his press was in Venice and two from the later period in Augsburg. Three of these examples of fine printing by this famous printer have been acquired by purchase from the Hiram Olsan Fund. In addition to providing excellent illustrations of the art of printing in its "cradle days," they offer scholars an opportunity to examine texts that were widely read and thus had great influence on thought in the fifteenth century.