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Letter against Werner

Frombork, 3 June 1524

Original: lost

16th century copies: Berlin, Staatsbibliothek Preussischer Kulturbesitz, Cod. Lat. Fol. 83, k. 8-10; Wien, Österreichische Nationalbibliothek, Sammlung von Handschriften und alten Drucken, Cod. 9737, fol. 1-9v; Oxford, Bodleian Library, Ms Saville 47, fol. 28-32v.; Uppsala, Astronomska Observatoriet, Coll. Hjörter, H III. 34; Schweinfurt, Stadtarchiv, Handschrift 1 Ha 14, fol. k. 9-13 v.

Copernicus' Letter against Werner was provoked by Johann Werner's work "Motion of the Eighth Sphere," published in his second collection of essays (Nuremberg, 1522).

Johann Werner was a Nuremberg vicar of St. John's and famous mathematician known for his works in spherical trigonometry, conic sections, cartography, as well as the first regular observations of the weather conditions in Germany.

Werner's "Motion of the Eighth Sphere" came to the notice of Bernard Wapowski (c. 1475-1535), the founder of Polish scientific cartography and a secretary of the king of Poland. Nowadays a book like Werner's second collection of essays would be reviewed in appropriate scientific periodicals. But these had not yet come into existence. In their absence Wapowski sought the opinion of his old friend Copernicus, who had been his fellow-student at the University of Cracow.

Knowing that Copernicus in far-off Frombork was not in touch with foreign cultural centers and developments, as he himself was, Wapowski sent Copernicus a copy of Werner's "Motion of the Eighth Sphere," remarking that it was widely praised, and requesting the astronomer's judgment.

What Wapowski sent Copernicus was not a complete copy of Werner's 1522 collection of essays, but only "The Motion of the Eighth Sphere". For, the preceding essays dealt, not with any astronomical problem, but with three purely mathematical topics: conic sections, uplication of the cube, division of a sphere in a given ratio.

When did Werner's essay (or 1522 collection of essays) reach Wapowski in Cracow? When did the royal secretary send "The Motion of the Eighth Sphere" to Frombork? Our only clue is Copernicus' use of an imprecise word at the outset of his reply:

Some time ago (pridem), my dear Bernard, you sent me alittle treatise on "The Motion of the Eighth Sphere.

Evidently Copernicus did not dash off an instant reply. Instead, on 3 June 1524 he sent Wapowski a carefully considered report, which has come to be known in the literature as his Letter against Werner.

Cast in the form of a private letter to Wapowski, it was not intended for publication. Nevertheless it has been called by Leopold Prowe an "open letter", "intended for the public, as is shown by its content and form," with the author "permitting the recipient to give it wider distribution"1. But nothing in the Letter against Werner authorizes further distribution. Nothing in its form shows that it was an open letter, intended for the public. Had that been Copernicus' purpose, he would surely have refrained from using such harsh language about Werner, whose work had been widely praised by others, as he was informed by Wapowski. Copernicus' Letter against Werner was a private communication to Wapowski, not intended for the general public.

For his part, Wapowski deemed the scientific content of the Letter against Werner to be too important to be shut up in his personal files. For in the first place, Copernicus' Letter against Werner made a notable contribution to the emerging discipline of chronology by correcting Werner's woeful error of eleven years in dating Ptolemy's catalog of fixed stars, a conspicuous landmark in the history of astronomy. Secondly, the Letter against Werner insisted on technical terms being defined and used with precision: in a recurring periodic nonuniform motion, the mean velocity cannot also be the slowest, although Werner would have it both ways. Lastly, the Letter against Werner maintained the primacy of fact over theory. Having constructed a theory in conflict with ancient observations, Werner concluded that the observations were wrong. On the contrary, Copernicus replied, the theory is wrong, being inconsistent with itself to boot. With regard to our attitude toward the ancient scientists, Copernicus writes that we must

hold fast to their observations, bequeathed like a legacy. But if anyone, holding fast to his own view, thinks that they are untrustworthy in this regard, surely the gates of this art are closed to him. Lying in front of the entrance, he will dream the dreams of the deranged about the motion of the eighth sphere, and receive what he deserves for supposing that he should support his own hallucination by defaming the ancients.

It has recently become somewhat fashionable to link Copernicus with Pythagoreanism, neo-Pythagoreanism, Neoplatonism, and hermeticism. The evidence adduced for such linkage would easily pass through the eye of a needle without noticeably deforming the needle. On the other hand, Copernicus' familiarity with the writings of Aristotle, that well-known critic of the Pythagoreans and Plato, is quite apparent in his Letter against Werner. Its opening paragraph quotes from the Metaphysics, mentioning Aristotle by name. Later on, it echoes a striking statement in Aristotle's Physics, without even alluding to that work or its author. Such familiarity with Aristotle's treatises does not of course make Copernicus an Aristotelian in the sense that he regarded the Stagirite as infallible. On the contrary, where he detected a flaw in Aristotle, as in the Stagirite's division of simple motion into three mutually exclusive types, he did not hesitate to correct it. But he did not undertake to overthrow Aristotelianism, as he did the Ptolemaic astronomy. On the other hand, what he believed was sound in both systems, he retained with gratitude and affection, an attitude which some of our contemporaries would do well to consider.

From Edward Rosen's Introduction published in:
Nicholas Copernicus Minor Works (Warsaw-Cracow, 1985).

1 Leopold Prowe, Nicolaus Copernicus, (Berlin, 1883), vol. I, part II, 221,223

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