The Sphere of Johannes de Sacrobosco

PREFACE.

utilities invites us to this doctrine, young students must cultivate it diligently. And in this matter, it is fitting for them to be moved also by the praises of their fatherland, because this doctrine, although it had lain without honor for some centuries, has recently flourished again in Germany, restored by two supreme men, Purbach and Regiomontanus, of whom one was born in Noricum the region of Bavaria and Austria, and the other in the neighboring Franconia. The thing itself bears witness that these heroes were divinely stirred with a singular power to illustrate these arts. For when did they have such light, after these studies were extinguished in Egypt? For although the Arabs invaded the possession abandoned by the Greeks with great force, to the point that they propagated these arts into the west and even into Spain, yet their writings show that that curious nation did not labor so much in observing the motions as in divinations, of which they were so greedy that, not content with the Astrology of Ptolemy, which can be considered a certain part of physics, they also invented oracles and many other types of predictions anypologēta without a logical basis. But our men devoted all their study to the principal part of the doctrine; they unearthed and revealed the most obscure demonstrations of Ptolemy, and so that the art might be transmitted to posterity, they instructed us with commentaries of more than one kind. The ancients praise the dove of Archytas and the various works of Archimedes; but a far more admirable work is that short little book, the Theoricae Purbachii Theories of Purbach, which, having encompassed the sum of the very long work of Ptolemy, subjects the arrangement of the spheres to the eyes. What shall I say of the remaining monuments, of the complete epitome, of the tables, in which, in order to complete the art, they showed the use of the precepts? Up to this point, therefore, the praise of this doctrine has been in the hands of our men. For those authors scattered the seeds of this doctrine throughout Germany, just as Triptolemus is written to have scattered grain seeds in Greece.