In my first article about Rensberger’s Astronomia Teutsch I mentioned that, unlike William Lilly, Rensberger would not reveal a lot about the sources he had available to him when he was writing his book. But after closer inspection of his work I have found a number of astrologers mentioned whose works he obviously was familiar with. Based on this information I wanted to create a hypothetical library Rensberger could have owned. It is of great interest to me to find out how the tradition was preserved over the centuries, or, in other words, through which channels the astrological knowledge was flowing into the West. I set out to reconstruct Rensberger’s library, purely based on the hints he gives us in his book. I can not tell if he used any early editions or had some astrological treasures stacked up in his library. Nevertheless what I tried to do was to create a library of books available at Rensberger’s lifetime, up to the publishing date of his Astronomia Teutsch in 1569. If possible I tried to supply him with the latest editions published close to the place where his book was published, Augsburg. In his Christian Astrology William Lilly enables us to have a virtual look at his bookshelves. This is fortunate because both, he and Rensberger, were pioneers translating astrology into their own language. This means that both of them could read the same or similar source material in Latin. Therefore we can postulate that they were drawing on similar material which is helpful in some ways.
I will begin with Claudius Ptolemy, who is mentioned frequently. He wrote an important astrological work, Quadripartite, which was published many times. In our case I would suggest that Rensberger had the edition from1549, which was printed in Nürnberg, on his bookshelf. Lilly owned the 1551 edition, printed in Basel, Switzerland. Rensberger mentions as well the book Centiloqium. He notes that some people say Ptolemy was not the author of this work; nevertheless he uses it as a source. Wüstenfeld claims in his book Die Übersetzung Arabischer Werke in das Lateinische, (the translation of Arab works into Latin), Göttingen 1877, “Ptolmaei Centiloquion is the book Librorum suorum fructus ad Syrum […] with the original in Escurial, one with a Persian comment in the Bodleian Library and another one in Leiden. The Latin translation generally appears with a comment by Ali ben Rudhwan”.
Another name that can be found in Rensberger’s book is Hermes. In the chapter dealing with the correspondences between Planets and parts of the human body Ptolemy’s and Hermes’ views are compared. If he quotes from Hermetis Centum aphorismorum liber in Nicolaus Pruckner’s edition of Firmicus Maternus, Johannes Hervagius, Basel 1551, or from his De revolutionibus nativitatum in Ptolemy’s Tetrabiblos edition by Heinrich Petri, Basel 1559 is not clear to me at the moment. Further research will hopefully clarify this.
Another astrologer mentioned by Rensberger is Proclus Diadochus. He quotes him in the chapter on Solar and Lunar eclipses. William Lilly has it in his bibliography under: Proclus – In Quadripartitum Ptolomei, folio, Basiliae, 1559.
Holden talks about a Latin edition by Leo Allatius, Leiden, 1635, but I found an earlier one: Proclus Diadochus, Paraphrasis in quatuor Ptolemi libros de siderum effectionibus. Cum prfatione Philippi Melanchthonis, 1554. A copy of this was supposedly in Dr. John Dee’s library.
The next famous astrologer, mentioned by Rensberger in connection with eclipses, is Guido Bonatus. I picked two editions here which could have been on our astrologer’s shelf. The first one is Tractatus astronomie, edited by Johannes Angelus, Augsburg, published by Erhard Ratdolt, 1491, the second one by Jakob Kundig, Basel, 1550, which Lilly owned as well. Bonatus is mentioned again, together with Hali, in connection with the great conjunction. We know that Bonatti held Hali in high esteem, which explains why Rensberger mentioned them together. Hali, as he is referred to, was really called Ali Abū al-Hasan ibn Abī al-Rijāl or Haly Abenragel or Albohazen Haly; his work Preclarissimus liber completus in judiciis astrorum, or Libri de judiciis astrorum (Kitāb al-bāri’ fī akhām an-nujūm) was first published by Erhard Ratdolt de Augusta in 1485 but I would go with the Basel edition by Heinrich Petri from 1551. Unfortunately it would take until 1571 for the edition to appear, which Lilly claims to be the only non defective one, sadly too late for our purposes here.
The astrologer Rensberger quotes more than anyone else is the famous Albumasar. His opus De magnis conjunctionibus which was published by Erhard Ratdolt, 1489, in Augsburg is the latest edition I know of. William Lilly owned this edition and so must have Rensberger.
Next to be mentioned in the text is Alcabitius. His book Astronomie judiciarie principia tractans cum Ioannis Saxonii commentario was printed by Guillaume Huyon for Barthelemy Trot, 1523 in Lyon. Rensberger quotes him in a chapter about the conjunctions between Saturn, Jupiter and Mars. In the same chapter he mentions another famous astrologer, Valentinus Naibod, who was a contemporary astrologer. His work with the title Enarratio elementorum astrologiae was published by Arnold Birckmann, 1560 in Cologne. Lilly calls it Ennaratio in Alcabitum, which gives an indication why these two men are mentioned together in Astronomia Teutsch.
Further on another famous Arab astrologer, Masha’allah, is quoted in Astronomia Teutsch. I would guess that Rensberger owned a copy of Opera Messahallica (De significationibus planetarum in nativitate, Liber receptionis, De revolutionibus annorum mundi, Epistola in rebus eclipsis, De cogitatione). This edition was published by Joachim Heller in Nuremberg, 1549.
Lucam Gauricum is another contemporary astrologer mentioned by Rensberger. His work Tractatus astrologiae judiciariae de nativitatibus virorum & mulierum was published by Johannes Petreius in Nuremberg in 1540 and will probably have found its way on the bookshelf of our astrologer.
The last person to be found in Rensberger’s textbook is not so much an astrologer as a mathematician and astronomer. It is the famous Johannes Müller, also known as Regiomontanus or Iohannis de Monte Regio. His work Tabulae directionum profectionum quetam was published in Augsburg in 1490 and in Tübingen by Ulrich Morhart in 1559. His house tables became fast the new standard.