In the popular version of the so-called astronomical revolution Andreas Osiander, who was born on the 19th December 1496 or 1498, is very often presented as the greatest villain in the history of science because he dared to suggest in the ad lectorum (to the reader) that he added to the front of Copernicus’ De revolutionibus that one could regard the heliocentric hypothesis as a mere mathematical model and not necessarily a true representation of the cosmos. Is the judgement of history just and who was Andreas Osiander anyway?

Andreas Osiander was born in Gunzenhausen, a small town to the south of Nürnberg, the son of Endres Osannder a smith and Anna Herzog. His father was also a local councillor, who later became mayor. He entered the University of Ingolstadt in 1515 where he, amongst other things, studied Hebrew under Johannes Reuchlin one of the greatest humanist scholars in Germany at that time, the great uncle from Philipp Melanchthon and the leading Hebrew scholar of the age. In 1520 Osiander was ordained a priest and called to Nürnberg to teach Hebrew at the Augustinian Cloister. This had been a major centre for reformatory debate for a number of years and it is here that Osiander became a religious reformer. In 1522 he was appointed preacher at the Saint Lorenz church in Nürnberg and became the leading voice for religious reform in the city. In 1525 Nürnberg, a city-state, became the first state to officially adopt the Lutheran Protestant religion, and Osiander became a highly influential and powerful figure. He was largely responsible for converting Albrecht of Prussia to Protestantism and also had a major influence on Thomas Cranmer, later Archbishop of Canterbury and author of the Common Book of Prayer. A trivial pursuits fact is that Cranmer married one of Osiander’s nieces.

Osiander’s first links with the printer/publisher Johannes Petreius was as the author of polemical religious tracts, which Petreius published. How he became an editor for Petreius is not know. It is also not known when and where Osiander developed his interest in and knowledge of the mathematical sciences. What is certain is that it was Osiander who, after Petreius had discovered Cardano’s books at the book fair in Frankfurt, who wrote to the Italian mathematician/physician/philosopher on Petreius’ behalf offering to publish his books in Germany; an offer that Cardano was more than willing to accept. Osiander then became the editor of those books of Cardano’s that Petreius published over the years; a service for which Cardano thanks him very warmly in the preface to one of his books, praising him highly for his abilities as an editor.

When Rheticus published his account of Copernicus’ heliocentric astronomy in his Narratio Prima, in the form of an open letter addressed to Johannes Schöner, another of Petreius’ editors, it was Osiander who wrote to Rheticus on behalf of the publishing house showing great interest in the cyclical astrological theory of history outlined by Rheticus in his little book.

After Rheticus had brought the manuscript of De revolutionibus to Nürnberg, Philipp Melanchthon pressured him to take up the professorship for mathematics in Leipzig and Osiander took over the task of seeing the text through the press. It is here that Osiander added the ad lectorum to the finished book, which has, over the centuries, pulled down so much odium on his head. Is this harsh judgement of his actions justified or have we, as I believe, been blaming the wrong man for the last four and a half centuries.

In the early days of printing there was no such thing as authors rights. The rights to a book lay with the printer/publisher, who was also the first port of call should the authorities decide that a book or pamphlet was seditious, blasphemous or in any other way unacceptable. And please remember our concepts of freedom of speech simply did not exist in sixteenth-century Europe. The ad lectorum was added to De revolutionibus certainly with Petreius’ knowledge and almost certainly at his instigation. This is confirmed by his reaction as Copernicus’ friend Bishop Tiedemann Giese complained to the city council of Nürnberg about the inclusion of the ad lectorum in his dead friend’s magnum opus. Consulted by the council on the subject Petreius basically flew off the handle and told them to get stuffed, it was his book and he’d put what the hell he liked in it.

Osiander continued to edit the books of Cardano for Petreius but in 1548 the city of Nürnberg accepted the Augsburg Interim an edict issued by Charles V, Holy Roman Emperor, who had just won a decisive victory against the Protestant forces, forcing the Protestant states within the Empire to revert to Catholicism. In a moonlight flit Osiander fled the city of Nürnberg and made his way north to Königsberg, where Albrecht appointed him professor of theology at the newly established university. This caused much bad blood, as Osiander was not a qualified theologian. In this position Osiander became embroiled in a major theological dispute with the supporters of Melanchthon in Wittenberg over the doctrine of justification. This dispute is known in German church history as the Osiander Dispute and led to a schism between the two parties, with Osiander basically forming his own branch of Protestantism.

Osiander died in 1552 a controversial figure both in the history of religion and the history of science. However as I have sketched above I think his bad reputation in the history of science is not really justified and the real villain of the piece, if there is one, is Johannes Petreius. I say if there is one, because many historians are of the opinion that the ad lectorum saved the De revolutionibus from being condemned straight away, when it was published, and allowed the heliocentric hypothesis it contained to spread relatively unhindered and become established.