Christmas Trilogy 2017: Bonus!

Yesterday was Johannes Kepler’s nominal birthday (as he was born before the calendar reform in a Protestant state his birthday on the Gregorian calendar would be 6 January!) and as in my wont, I posted a birthday post for the good Johannes. Of course I was far from being the only person to acknowledge his birthday and amongst many others somebody linked to the 2016 article on the website of the popular science magazine, Physics Today. Upon reading this brief tribute to my favourite seventeenth century polymath I cringed inwardly and didn’t know whether to let out a prolonged #histsigh or to turn loose the HistSci_Hulk; I have decided on the latter. Below the complete text of the offending document:

Born on 27 December 1571 in Weil der Stadt in the Holy Roman Empire, Johannes Kepler was an astronomer whose careful measurements led him to develop his three laws of planetary motion. He received a Lutheran education at the University of Tübingen and originally planned to be a theologian. Then one of his teachers gave him a copy of a book by Nicolaus Copernicus, sparking Kepler’s interest in astronomy. In 1600 Danish astronomer Tycho Brahe invited Kepler to Prague to help amass a precise set of astronomical measurements. Brahe died the following year, and Kepler inherited his mentor’s data and position as imperial mathematician to the Holy Roman emperor. In 1609 Kepler published Astronomia Nova, which included his first two laws of planetary motion; his third law was published in 1619. Kepler observed a supernova (though he called it a “new star”) and completed the detailed astronomical tables Brahe had been so determined to produce. Kepler also contributed research in optics and vision. Later in the century Isaac Newton would prove his law of universal gravitation by showing that it could produce Kepler’s orbits.

Born … in Weil der Stadt in the Holy Roman Empire… This contains something about which I have had bitter disputes on Wikipedia. There is a famous quip that the Holy Roman Empire was neither holy nor Roman nor an empire, it was also neither a country nor a state. The Holy Roman Empire was a loose feudal conglomeration of autonomous and semi-autonomous states. Weil der Stadt, Kepler’s birthplace was at the time of his birth in the autonomous Duchy of Württemberg.


Map of the Duchy of Württemberg 1619 by Pieter van den Keere. You can see Weyl (Weil der Stadt) roughly in the middle. Source: Wikimedia Commons

…Johannes Kepler was an astronomer whose careful measurements led him to develop his three laws of planetary motion. Kepler was a theorist, who didn’t on the whole take measurements careful or otherwise. The measurements that he used to derive his three laws were, of course, made very carefully by Tycho Brahe.

Kepler did not originally plan to be a theologian. He was on an educational tack designed to produce Lutheran Protestant pastors and schoolteachers. He would have become a pastor but was appointed to a position as a maths teacher instead.


Then one of his teachers gave him a copy of a book by Nicolaus Copernicus, sparking Kepler’s interest in astronomy. One of Kepler’s professors in Tübingen was Michael Maestlin, who in his courses taught Copernican heliocentric astronomy alongside the then dominant geocentric astronomy. Kepler took this course and developed an interest in heliocentrism. It was Maestlin who recognised Kepler’s aptitude for mathematics and recommended that he be appointed to a teaching post rather than a village church.

In 1600 Danish astronomer Tycho Brahe invited Kepler to Prague to help amass a precise set of astronomical measurements. Tycho Brahe invited Kepler to Prague not to help amass a precise set of astronomical measurements but to use his mathematical skills to turn the already amassed measurements into calculated orbits, ephemerides etc.

Brahe died the following year, and Kepler inherited his mentor’s data and position as imperial mathematician to the Holy Roman emperor. Kepler didn’t inherit his mentor’s data, Tycho’s daughter Elizabeth and her husband Frans Gansned Genaamd Tengnagel van de Camp did. This caused Kepler no end of problems, as he needed that data to realise his vision of a heliocentric astronomy. After tough negotiations, Tengnagel allowed Kepler to use the data but only if his name was included as co-author on any books that Kepler published based on it; a condition that Kepler duly fulfilled. Given my own inabilities to spell or write grammatically I’m not usually a grammar fetishist but, as I’m putting the boot in, Imperial Mathematician is a title and should be written with capital letters as in the emperor in Holy Roman Emperor.

Kepler observed a supernova (though he called it a “new star”). Well yes, as the term supernova was only coined in 1931 Kepler could hardly have used it. However, the nova part of the name, which simple means new, comes from Kepler’s term Stellar Nova, his being the most recent supernova observed with the naked eye.

…and completed the detailed astronomical tables Brahe had been so determined to produce. Kepler didn’t just complete them he produced them single-handedly, calculating, writing, typesetting, printing, publishing and selling them. This was the task assigned to him by Tycho and to which he was official appointed by the Emperor Rudolph II.

Physics Today is a fairly major popular science magazine but it would appear that they don’t really care enough about the history of science to indulge in a modicum of fact checking.






Filed under History of Astronomy, History of science, Myths of Science, Renaissance Science, Uncategorized

13 responses to “Christmas Trilogy 2017: Bonus!

  1. A vintage Tc post. I wonder who the author was, my own criticism would be that they didn’t really capture the nature of Kepler ‘s contribution.
    I wonder why the piece was published in 2016. I remain baffled by the ‘ on this day’ meme

  2. > teachers gave him a copy of a book

    Just curious but is that even plausible; as in, how much did books cost then?

  3. Added a comment at the offending site:

    Phillip2 • a few seconds ago Hold on, this is waiting to be approved by Physics Today.

    (Note: my standard avatar didn’t go through.

    • Reloading the page doesn’t show my comment. Rather, it shows:

      Comments are held for moderation by Physics Today staff. Off-topic statements and personal attacks will not be approved.
      Please read our Comment Policy before commenting.


      • Their comment policy says that discussion should be evidence-based. But they don’t allow the evidence. Instead of just posting the link, I added some text explaining what your post is about and suggesting that readers should make up their own minds. Again, removed without comment.

        This casts a really bad light on Physics Today.

        I suggest that you write a formal letter to the editor and post the rejection notice, if any, here.

      • Physics Today published a piece about Kepler, Thony wrote a critique of it, and the magazine doesn’t even allow the latter to be mentioned in comments. This is a new low. Other readers here should try to post comments linking to Thony’s piece or, perhaps better, write them a letter (on paper, registered post) saying that they are slapping scientific debate in the face.

    • Credit where credit is due: I got an email from Physics Today saying that my comments weren’t meant to be deleted, but that there was a problem with moderation during the holidays. My latest comment is now there (it’s the only one necessary now), linking back to your piece, and apparently they have also updated their own piece.

      (In my own defense (and I comment often on a lot of blogs, as a quick internet search will show), if moderation is there either the comment goes away immediately (often with a notice that moderation is in effect, though some sites forget this), or it is visible only to the commentator until approved and then visible to all (or rejected, in which case it is no longer visible to the commentator). I have never seen a posted comment sit there for a few minutes—regardless of whether moderation is in effect or not—then disappear.)

  4. David Love

    I completely agree that the article you are criticising is full of inaccuracies. However, I would like to take issue with you on two of your points:
    1. You say that “Maestlin ….. recommended that he be appointed to a teaching post rather than a village church.” What is the source for this statement, please? Kepler’s own autobiographical notes (in Astronomia Nova, Chapter 7) state that “I was driven to take on this [teaching] task [in Graz] by the authority of my teachers.” There is no mention of Maestlin here. Also, it is clear from the other comments that Kepler makes here that he deeply resented going to the teaching post in Graz. Given his clear admiration for Maestlin, it seems unlikely that this admiration would have survived if Maestlin had been responsible for sending him to a post that he very clearly didn’t want. Far more likely that it was the teachers who were suspicious of his Calvinist tendencies and/or his open espousal of Copernicanism (in what proportion each was responsible is unclear). So I don’t think it was Maestlin – unless you have a specific primary source that says otherwise.
    2. Although it may be technically correct to say that Kepler was born “in the autonomous Duchy of Württemberg”, it is more accurate to say that he was born in the Free Imperial City of Weil der Stadt (one of 80 or so largely self-governing cities within the Holy Roman Empire). He was born “in” Württemberg only in the sense that Weil der Stadt was surrounded on all sides by Württemberg.

    • You are of course quite right about Weil, it was indeed one of the Free Imperial Cities. However one should note that when Kepler was five-years-old his father renounced his citizenship of Weil and the family moved to Leonberg, which is definitely in Württemberg. Also Kepler received his whole education via a stipend from the Duchy of Württemberg, which meant that he was feudally bound to the Duchy for his whole life.

      Having read you book I am well aware of your hypothesis that Kepler was sent to Graz as a schoolteacher as punishment, however it suffers from several flaws. There is no evidence of Kepler being reprimanded in anyway whatsoever for his religious views during this period. As far as Kepler’s Copercanism is concerned he was hardly going to be punished for being interested in an astronomical theory that his mathematics professor was teaching openly in the same school. In fact the teaching of instrumental Copernicanism was widespread in Lutheran education institution in this period.

      However the major flaw in your argument is that its central premiss is the myth that Kepler’s theology studies where broken off shortly before completion by sending him to Graz. Kepler never studied theology in that sense and there was no course to be completed.

      Kepler was in a programme to train students to become either pastors or schoolteachers within the Lutheran Protestant system. This programme closed with completion of the MA degree, for Kepler in August 1591. Having graduated, those in the programme remained at the university doing general pedagogic and theology courses until such time as a suitable post was found for them. Kepler was in this post graduation stream, which had no final exams or completion date, when he was assigned to the post in Graz. No studies were interrupted, no course broken off shortly before completion, that is simply a myth.

      That Maestlin recommended Kepler for the position is simply logical. Th Lutheran authorities in Graz sent a request to Tübingen for a combined schoolteacher for mathematics and district mathematician. As the only professor for mathematics in Tübingen at the time Maestlin would have been asked to recommend a suitable candidate, he recommended his best student, Kepler.

      • David Love

        Thank you for these comments. In response:

        1. You are of course correct that Kepler’s family moved to Leonberg when he was a child (I have visited their first house there – it is now a clothes shop!). However, the issue was where he was born, not where he moved to, and he was undoubtedly born in Weil der Stadt, not Württemberg.

        2. I see that it is your own conclusion that Kepler was recommended for the Graz post by Maestlin, rather than something that appears in any primary source document. I’m afraid that I still consider your conclusion implausible. Kepler’s own words on the subject include the following:
        “protesting loudly that I would never willingly concede my intention to follow another kind of life which seemed more splendid”, and
        “However, to tell the truth I was driven to take on this task by the authority of my teachers.” and
        “the low opinion and contempt in which this kind of [teaching] function is held”.
        These quotations from Kepler clearly indicate not just that he really didn’t want to go to the teaching post in Graz, which he (and everybody else) saw as a very inferior position, but also that he only did so because of “my teachers”. Surely if it really had been Maestlin who had recommended him, he would have said so somewhere – but he doesn’t. And surely if Maestlin held Kepler in such high regard (which he did), Maestlin would not have wanted Kepler to move to a post that everyone regarded as inferior. And finally, surely Kepler – who was often quick to take offence, at least in his early years – would subsequently have been bitter towards Maestlin (which he wasn’t) if Maestlin was indeed responsible for the Graz move.

        3. My own conclusion that Kepler was sent to Graz (in spite of his brilliance) because he was not regarded as suitable material for a Lutheran minister (whether because of his Copernican beliefs or his Calvinistic streak) is actually shared by others. For example, Alexander Koyré (in “The Astronomical Revolution”) states:
        “The official documents are full of eulogies bestowed on Kepler. Nevertheless, it is probable that he was already regarded with suspicion by orthodox Lutheranism on account of his avowed and enthusiastic partisanship of Copernican cosmology, and that the university authorities sent him to Graz to a post socially inferior to that of a pastor in order to get rid of him.”
        J L E Dreyer (in “Tycho Brahe”) states:
        “He completed his studies in the faculty of Arts, and took the Master’s degree in 1591, after which he entered the theological faculty, and spent the next two years in studying the intensely narrow-minded dogmas which then prevailed in the Lutheran Church, and which were so distasteful to him that he was soon known among theologians as one unfit for a clerical career.”
        Arthur Koestler, in his reworking of Max Caspar’s biography, puts it a little more gently:
        “Perhaps they wanted to get rid of the querulous young man, who had professed Calvinist views and defended Copernicus in a public disputation.”
        I can’t find any source anywhere that agrees with your own idea that it was on Maestlin’s recommendation that Kepler went to Graz.

        4. Max Caspar himself, even though he rejects the idea that Kepler was thrown out because of his Calvinistic streak (perhaps influenced by Caspar’s own devout Lutheranism), nevertheless indicates that Kepler had not come to the end of his studies in Tübingen before he had to leave for Graz, as do other sources.

        5. I don’t think you can conclude (as you seem to) that Maestlin taught Copernicanism as literally true. Caspar is in no doubt that Maestlin sided publicly with Ptolemy, both in his lectures and in his writings, if only for the reason that Copernicanism was in conflict with a number of passages in the Bible. I think it is far more likely that Maestlin did no more in public than maintain (as had Osiander) that Copernicanism was simply a useful calculating device. Any statement that Copernicanism was literally true could only have been made privately.

      • 2) Kepler might have regarded teaching as inferior but this was certainly not the opinion of the Lutheran Protestant Church. Philip Melanchthon, Luther’s Preceptor Gemania, put a lot of thought and effort into creating a modern school system for the Church and was very innovative in that he gave mathematics a high priority in his educational system. You write “everybody else saw it as a very inferior system”, would you care to back up this generalisation with some facts, sources…?
        Kepler’s relationship with Maestlin was anything but smooth or harmonious. Maestlin reprimanded him several times for what he saw as intellectual failings and also ignored him on more than one occasion when Kepler came begging for help. However, Kepler never criticised him for these examples of extremely bad behaviour towards his pupil, so your claim that Kepler would have criticised Maestlin for recommending him for the post in Graz simply doesn’t hold water.

        3) &4) Clearly illustrate the problem with your argument all the sources that you quote are old and dated. You simply ignore all and any recent research. Koyré you can forget he lived in the age of the conflict between science and religion, a long debunked hypothesis built on prejudice rather than historical research. Dreyer is simply out of date. Casper’s claim that Kepler did not come to the end of his studies, which of course everybody else is channelling, is not supported in anyway by evidence, sources or anything at all. Charlotte Methuen in her Kepler’s Tübingen: Stimulus to a Theological Mathematics (1998) did go and research the sources, going very carefully through the archives of Tübingen University and proved that Kepler was not a theology student after completing his MA and his studies were not broken off when he was sent to Graz

        5) Maestlin taught Copernican cosmology and astronomy openly in Tübingen, modern research has clearly shown that to be the case, and whether he taught it as factually correct or simply as instrumentally useful is irrelevant to the fact that Kepler being a proto-Copernican as a student in Tübingen would not have been regarded as a cardinal sin.

        In all of your arguments you blithely ignore that fact that Kepler had a stipend for a specific course designed to train students to become either pastors or schoolteacher, Kepler knew this from the very beginning of his studies. That he had set his heart on becoming a pastor and was bitterly disappointed when his teachers considered him a suitable candidate to fill an important vacancy as a maths teacher is understandable but in no way leads to a conclusion that he was being punished in anyway whatsoever. Also it should be remarked that a village pastor was almost certainly not regarded as superior to a schoolteacher, particularly not in a Church that laid great importance an high quality education.

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