In 1542 the manuscript of De revolutionibusarrived at Petreius’ printing office in Nürnberg followed by Rheticus who intended to see it through the press. I argued in Part VII that Johannes Petreius had in fact commissioned Rheticus to see if Copernicus had written anything substantial on his astronomical theories and if so to persuade him to allow Petreius to publish it. Petreius’ printing office was certainly the right address for the publication of a major new work on astronomy, as he was certainly the leading scientific publisher–astrology, astronomy, mathematics–in the Holy Roman Empire of German States and probably the whole of Europe but who was Johannes Petreius?
The Petreius printing office in Nürnberg Photo by the author
He was born Hans Peter, whereby Peter is the family name, into a family of wealthy farmers in the Lower Franconia village of Langendorf near Hammelburg in 1496 or 1497. He matriculated at the university of Basel in 1512, graduating BA in 1515 and MA in 1517. He next appears as a witness in a court case in Basel in 1519, where he is described, as working as a proofreader for the Basler printer publisher Adam Petri. This explains why he had chosen to study in Basel, as Adam Petri was his uncle. Petri is the Swizz German version of the name Peter. Presumably, having learnt the black art, as printing was known, from his uncle he moved to Nürnberg in 1523 and set up his own printing office. The was almost certainly an attempt by the Peter family to cash in on the gradual collapse of the Koberger printing office following the death of Aton Koberger in 1513. The Petri-Froben-Amerbach printing cooperative had been Koberger’s licensees in Basel, printing his titles on commission.
Source: Wikimedia Commons
Hans Peter now sporting the Latinised name, Johannes Petreius, succeeded in establishing himself against the local competition and by 1535 was the leading printer publisher in Nürnberg. Like most other printer publishers Petreius’ main stock in trade was printing religious volumes but in the 1530s he began to specialise in printing scientific texts. Exactly why he chose to follow this business path is not known but it was probably the ready availability of the large number of mathematical, astrological and astronomical manuscripts brought to Nürnberg by Regiomontanus when he set up his own printing office in 1471. This hypothesis is supported by the fact that several of Petreius’ earliest scientific publications were all of manuscripts from this collection, all of which were edited for publication by Johannes Schöner, who would later be the addressee of Rheticus’ Narratio Prima.
This series of publications started with Schöner’s edition of Regiomontanus’ own De Triangulis in 1533, a very important work in the history of trigonometry. This was also one of the volumes that Rheticus took with him to Frombork, as a present for Copernicus.
Schöner followed this with Regiomontanus’ Tabulae astronomicaein 1536. Petreius’ activities in the area were not however restricted to Schöner’s output. Earlier he published the first Greek edition of Ptolemaeus’ Tetrabiblos, under the title Astrologica, edited by Joachim Camerarius (1500–1574), which included Camerarius’ translation into Latin of Books I & II and partial translations of Books III & IV together with his notes on Books I & II and the Greek text of the Centiloquium, a collection of one hundred astrological aphorism falsely attributed to Ptolemaeus, with a Latin translation by Giovanni Pontano (1426–1503).
Opening chapter of the first printed edition of Ptolemy’s Tetrabiblos, transcribed into Greek and Latin by Joachim Camerarius (Nuremberg, 1535). Source: Wikimedia Commons
A year earlier Petreius had published Johann Carion’s Practica new – auffs 1532 mit einer auslegung des gesehen cometen. Through these publications it is clear that the principle interest is in astrology and it is here that money was to be made. Over the next twenty plus years Petreius published more texts from Regiomontanus edited by Schöner, some of Schöner’s own works on astronomy and cartography, reckoning and algebra books from Christoph Rudolff (c. 1500–before 1543) and Michael Stifel (1487–1567). Various scientific texts edited by Peter Apian including his and Georg Tannstetter’s edition of Witelo’s Perspectiva (1535), another of the volumes that Rheticus took with him to Frombork for Copernicus. Various Arabic astrological texts, the Tractatus astrologicae (1540) of Lucas Gauricus (1575–1558), who along with Schöner and Cardano was one of the most important astrologers of the first half of the sixteenth century. Petreius became the publisher of Gerolamo Cardano (1501–1576) north of the Alps, publishing his works on mathematics, astronomy, medicine, astrology and philosophy, all of which were highly successful.
Source: Wikimedia Commons
He also published alchemical works from Abū Muḥammad Jābir ibn Aflaḥ better known in the West as Geber. As well as all this, Petreius commissioned and published the first German translation of Vitruvius’ De architectura, a bible for Renaissance artist-engineers.
Petreius’ scientific catalogue was very wide but also had depth, including as it did various classics by Regiomontanus, Schöner, Stifel, Cardano and Witelo. If anybody could adequately present Copernicus’ masterpiece to the world then it was Johannes Petreius.
Rheticus had originally intended seeing Copernicus’ manuscript through the press but Philipp Melanchthon had other plans for his errant protégée. In the meantime Rheticus had, at the request of Joachim Camerarius, who was now rector of the University of Leipzig and had obviously been impressed by Rheticus during their meeting in Tübingen, been offered a chair in mathematics at Leipzig.
Joachim Camerarius, 18th-century engraving by Johann Jacob Haid. Source: Wikimedia Commons
In the autumn of 1542 Rheticus, under pressure from Melanchthon, left Nürnberg and preceded to Leipzig, where he was appointed professor of higher mathematics i.e. astronomy and music and his direct involvement in De revolutionibus came to an end. Petreius still needed an editor to see Copernicus’ weighty tome through the press and this duty was taken over, with serious consequences by Nürnberg’s Lutheran Protestant preacher, Andreas Osiander (1496 or 1498–1552).
Andreas Osiander portrait by Georg Pencz Source: Wikimedia Commons
Osiander was born in the small town of Gunzenhausen to the south of Nürnberg, the son of Endres Osiander a smith and Anna Herzog. His father was also a local councillor who later became mayor. He matriculated at the University of Ingolstadt in 1515 where he, amongst other things, studied Hebrew under the great humanist scholar and great uncle of Melanchthon, Johannes Reuchlin. In 1520 he was ordained a priest and called to Nürnberg to teach Hebrew at the Augustinian Cloister, a hot bed of reformatory debate, where he also became a reformer. In 1522 he as appointed preacher at the St Lorenz church and became a leading voice for religious reform. Osiander achieved much influence and power in Nürnberg when the city-state became the very first Lutheran Protestant state.
Osiander first became involved with Petreius when the latter started publishing his religious polemics. Petreius also published numerous religious works by both Luther and Melanchthon. Where or how Osiander developed his interest and facility in the mathematical sciences is simply not know but they are attested to by Cardano in the preface to one of his books published by Petreius. In fact it was Osiander, who was responsible for the correspondence between Cardano and the Petreius printing office and he edited Cardano’s books there. When or how Osiander became an editor for Petreius is also not known. In his capacity as editor of De revolutionibus Osiander committed what many have as one of the greatest intellectual crimes in the history of science, he added the infamous ad lectorum, an address to the reader with which the book opens.
The ad lectorum is an essay that it pays to read in full but here we will just consider the salient points, Osiander writes:
There have already been widespread reports about the new novel hypothesis of this work, which declares that the earth moves whereas the sun is at rest in the centre of the universe.
Here Osiander lets us know that knowledge of Copernicus’ heliocentric hypothesis was already widespread–spread by the Commentariolus, the Narratio Prima and by rumour–indicating that there was going to be a high level of expectancy to learn the mathematical details of the system. He goes on:
Hence certain scholars, I have no doubt, are deeply offended and believe that the liberal arts, which were established long ago on a sound basis, should not be thrown in confusion.
Anticipating criticism from conservative circles Osiander goes into defensive mode:
But if these men are willing to examine the matter closely, they will find that the author has done nothing that is blameworthy. For it is the duty of an astronomer to compose the history of the celestial motions through careful and expert study. Then he must conceive and devise the causes of these motions or hypotheses about them. Since he cannot in any way attain to the true causes, he will adopt whatever suppositions enable the motions to be computed correctly from the principles of geometry for the future as well as the past.
Here we have the crux of Osiander’s defence. Astronomers are here to produce geometrical models in order to provide accurate predictions of celestial motions and not to determine the unobtainable true causes of those motions. This argument has been dubbed instrumentalist and some hail Osiander as the first instrumentalist philosopher of science. Instrumentalism is a metaphysical attitude to scientific theories that enjoyed a lot of popularity in modern physics in the twentieth century; it doesn’t matter if the models we use describe reality, all that matters in that they predict the correct numerical results. Osiander expands on this viewpoint:
For these hypotheses need not be true or even probable. On the contrary, if they provide a calculus consistent with the observations, that alone is enough.
Here we have the core of why the ad lectorum caused so much outrage over the centuries. Osiander is stating very clearly that the mathematical models of astronomers are useful for predictive purposes but not for describing reality. A view that was fairly commonplace over the centuries amongst those concerned with the subject. Copernicus, however, very clearly deviates from the norm in De revolutionibus in that he presents his heliocentric system as a real model of the cosmos. Osiander’s ad lectorum stands in clear contradiction to Copernicus’ intentions. Osiander then goes into more detail illustrating his standpoint before closing his argument as follows:
…the astronomer will take as his first choice that hypothesis which is easiest to grasp. The philosopher will perhaps rather seek the semblance of the truth. But neither of them will understand or state anything certain, unless it has been divinely revealed to him.
Here we have Osiander restating the standard scholastic division of responsibilities, astronomers provide mathematical models to deliver accurate predictions of celestial motions for use by others, philosophers attempt to provide explanatory models of those motions but truth can only be delivered by divine revelation. The modern astronomy, whose gradual emergence we are tracing had to break down this division of responsibilities in order to become accepted as we shall see in later episodes. Osiander closes with a friendly appeal to the reader to permit the new hypotheses but not to take them too seriously, and thereby make a fool of himself.
Therefore alongside the ancient hypotheses, which are no more probable, let us permit these new hypotheses also the become known, especially since they are admirable as well as simple and bring with them a huge treasure of very skilful observations. So far as hypotheses are concerned, let no one expect anything certain from astronomy, which cannot furnish it, lest he accept as the truth ideas conceived for another purpose, and depart from this study a greater fool than he entered it. Farewell.
There is a widespread belief that Osiander somehow smuggled his ad lectorum into De revolutionibus without the knowledge of either Copernicus or Petreius but the historical evidence speaks against this. There are surviving fragments of a correspondence between Osiander and Copernicus that make it clear that Osiander discussed the stratagem of presenting De revolutionibus as a hypothesis rather that fact with him; although we don’t know how or even if Copernicus reacted to this suggestion. More telling is the situation between Petreius and Osiander.
There is absolutely no way that Osiander could have added the ad lectorum without Petreius’ knowledge. This is supported by subsequent events. When the book appeared Tiedemann Giese was outraged by the presence of the ad lectorum and wrote a letter to the city council of Nürnberg demanding that it be removed and the book reissued without this blemish. The council consulted Petreius on the subject and he let them know in no uncertain terms that it was his book and what he put in it was his business and nobody else’s.
Petreius’ reaction illustrates an important point that modern commentators often overlook. Our concept of copyright didn’t exist in the sixteenth century, the rights to a publish work in general lay with the publisher and not the author. This is clearly demonstrated by the fact that when a publication provoked the ire of the authorities, civil or clerical, it was the printer publisher, who first landed before the court and then in goal rather than the author.
The ad lectorum was anonym but any reader, who was paying attention should have realised through the phrasing that Copernicus was not the author. The Nürnberger astronomer and instrument maker Johannes Pratorius (1537–1615), another Wittenberg graduate, wrote in his copy of De revolutionibus that Rheticus, when Pratorius visited him in 1569, had revealed to him that Osiander was the author of the ad lectorum.
Source: Wikimedia Commons
Michael Maestlin’s copy contains the same information also from Rheticus via Peter Apian. Kepler’s second hand copy had this information added by its original owner Hieronymus Schreiber (birth date unknown–1547), yet another Wittenberg graduate, who had received a gift copy signed by Petreius, because he had substituted for Rheticus in Wittenberg during the latter’s time in Frombork. All of this indicates that Osiander’s authorship of the ad lectorem was circulating on the astronomers’ grapevine by 1570 at the latest. It was first put into print, and thus made general public, by Kepler in his Astronomia Nova in 1609.
As with most books in the Early Modern Period there was no publication date for De revolutionibus but it seems to have been finished by 20thApril 1543, as Rheticus signed a finished copy on this date. According to a legend, put in the world by Tiedemann Giese, Copernicus received his copy, which was placed into his hands, on his dying day the 24thMay 1543. Owen Gingerich, who is the expert on the subject, estimates that the 1stedition probably had a print run of about 400 copies, which carried the mathematical details of Copernicus’ hypothesis out into the wide world.