This is the sixth and final episode in a series of discussions of selected parts of Paul Strathern’s The Other Renaissance: From Copernicus to Shakespeare, (Atlantic Books, 2023). For more general details on both the author and his book see the first post in this series.
The heading of today’s chapter is Brahe and Kepler, which immediately provokes a strange reaction in my brain. The is an unwritten convention in English that if one refers to Tycho Brahe by a single name then it is Tycho and not Brahe and by Johannes Kepler then it is Kepler not Johannes., so my brain says the chapter heading should be Tycho & Kepler. Why this is I have no idea and have often spent time wondering about it. Conventional use of names is a strange area that appears to defy logic. Galileo Galilei is almost always simply Galileo in English but in German he is Galilei, but I digress.
With this final chapter we are also scraping the barrel in terms of Strathern’s historical idiocies. It goes without saying that he pays far more attention to the long list of Tycho’s personal oddities than he does to his actual achievements in the history of astronomy. Quite often I couldn’t help getting the feeling that he actually just makes shit up. I have read an awful lot of literature on both of these astronomers, and I kept stumbling across statements that were not simply false but which I had never come across anywhere before. Let us begin. The opening paragraphs are pure purple prose of the worst sort and historically inaccurate:
Sometime during the 1590s, Richard Burbage and his players were invited by the King of Denmark to perform a lucrative summer season at the royal castle at Elsinore (Helsingør). Shakespeare was not amongst these players, but would later be regaled with tales of their foreign adventure. These would provide the background for the play he had in mind, whose full title would be Hamlet, Prince of Denmark.
It is at night on the battlements of Elsinore Castle that Hamlet encounters his father’s ghost, whose revelations sow the seeds of the ensuing tragedy. Coincidentally, some years earlier, while pacing these same battlements, the King of Denmark had suddenly seen the solution to a problem that was troubling him.
King Frederick II had taken under his wing an aristocratic young astronomer called Tycho Brahe, whose behaviour was as eccentric as his appearance: he wore a false metal nose and his awkward paranoid character inclined him to flamboyant cantankerous outbursts. [bullshit!] Brahe’s most recent astronomical observations had made him famous throughout Europe, and the king knew that Brahe was planning to leave Denmark. Brahe had received an offer to set up in Basel, one of the leading intellectual centres in Europe: home of the artistic Holbeins; where Paracelsus had briefly been professor; location of the skilled printer Oporinus to whom Vesalius had entrusted his masterwork. Looking out over the sea, Frederick II’s eye happened to alight on the remote island of Hven, in the middle of the Øresund (Sound) between Denmark and Sweden. Hven was royal territory, occupied only by a small village of fisherfolk and smallholders. If he offered Brahe this island, where the astronomer could build his own private residence, perhaps this would tempt him to remain in Denmark.
Although I studied English literature, amongst other things, at university I’m not a Shakespeare expert. There is a vast amount of literature about the possible sources of Hamlet. However, it is possible that Shakespeare did take Elsinore, as the setting for his play, from visiting actors but not from Richard Burbage and not from the 1590s. When Kronburg, the royal castle in Helsingør, was inaugurated in 1585, three English actors–William Kemp, Thomas Pope, George Bryan–performed there. Later the three, together with Shakespeare established the acting company, The Lord Chamberlain’s Men.
In 1575, when the scene Strathern is describing took place, Frederick II, would not have been pacing those same battlements, as the Kronburg was still being constructed. The suggestion that Tycho should be given his own observatory came from the astronomer Wilhelm IV Landgraf von Hessen-Kassel (1532–1592), whom Strather never mentions, but should have, Wilhelm was related by marriage to Frederick. His sister was married to one of Frederick’s uncles. The suggestion to let Tycho use Hven probably came from Tycho’s uncle Steen Bille. Frederick had already offered Tycho the choice of a traditional fiefs and honours as was his due as a high-ranking aristocrat, but Tycho had demurred. Steen Bille made Frederick aware that Tycho did not want the responsibilities and duties that went with a conventional fief, as they would interfere with his astronomical work, it was then that Frederick made his offer with a rhetorical flourish.
“…when he had been at Helsingør recently, checking on the construction of Kronborg Castle Frederick’s glance had happened to fall on the little island of Hven, on the southeast horizon. This he thought, was a perfect place for Tycho: isolated, unassociated with any administrative obligations, and unbound to any noble in fief. If the royal exchequer were tapped for the expenses of founding and maintaining a proper establishment, was there anything that Tycho hoped tom do abroad that he could not do here, where it would rebound to the credit of his country, his king and himself.”[1]
Strathern further:
Brahe had received an offer to set up in Basel, one of the leading intellectual centres in Europe: home of the artistic Holbeins; where Paracelsus had briefly been professor; location of the skilled printer Oporinus to whom Vesalius had entrusted his masterwork.
Although Tycho was planning on moving to Basel he had received no such offer to do so. One has to ask if Strathern thought that Tycho wanted to go ghost hunting in Basel? Remember we now have 1575, Hans Holbein the Younger was last in Basel in 1532 and had in fact died in 1543, his elder brother Ambrosius had already died in 1519. Oporinus was somewhat closer to Tycho’s times dying in 1563, as for Paracelsus, the city of Basel would prefer not to remember his brief stay there, less than a year, and he had departed the planet in 1541!
Strathern now heads off into his usual collection of fairy tales, avoiding facts in favour of sensation.
Tycho Brahe was amongst the more exotic characters to have contributed to the northern Renaissance. He came from a high-flying but dysfunctional noble family. His father, Otte, was the resident governor of a succession of royal castles (and may even have been a temporary governor of Elsinore). Tycho’s uncle Jørgen, who had inherited the considerable family fortune, was a royal counsellor, naval hero and hard-drinking pal of Frederick II.
The Brahe family was anything but dysfunctional and I have no idea where Strathern got this idea from. Otte’s career was more successful than Jørgen’s, he held a series of important fiefdoms and was indeed governor of Helsingborg Castle. There was no law of primogeniture in Denmark, so Jørgen did no inherit the considerable family fortune. As the only two children of Tyge Brahe and Sophie Rud, Otte and Jørgen both inherited, receiving equal shares. Otte became a Rigsraad (royal counsellor), Jørgen didn’t.
When Jørgen discovered that he could not have children, he decided that he would select his own heir. In pursuance of this aim, he bullied his younger brother Otte into promising that he would present him with his firstborn son.
Otte’s disappointment with this arrangement was allayed when his wife gave birth to twin boys. Unfortunately, the other twin died in infancy, and Uncle Jørgen turned up to collect Tycho when he was just two years old. (Some reports claim that Tycho was kidnapped.) Tycho’s father threatened to murder his older brother, but nothing came of this.
Tycho’s own account:
His uncle Jørgen “without the knowledge of my parents (took) me away with him while I was in my earliest youth [and] brought me up and thereafter supported me generously during his lifetime … and always treated me as his own son.”[2]
There is no record of Otte Brahe threatening to kill Jørgen. Jørgen’s justification seems to have been that he and his wife Inger Oxe couldn’t have children. He seems to have waited till Tycho’s younger brother, Steen, had passed the greatest uncertainties of infancy, before abducting Tycho.
Tycho’s childhood was passed in a succession of cold draughty castles on the Baltic coast, dining at long wooden tables crammed with innumerable relatives. At the head of the table sat the intimidating figure of Uncle Jørgen; topics of mealtime conversation were ‘warfare, politics and court gossip’.
Tycho’s childhood was no different to that of any aristocratic child growing up in sixteenth-century Denmark. The only difference to his biological family is that he was, in his foster family, an only child. Fostering was, for various reasons, not unusual amongst the Danish aristocratic families, so Tycho’s situation was not so strange.
Otte wished his son to be educated in Latin, but Jørgen did not believe in such fripperies. Ten years before Tycho’s birth, in 1536, Denmark had broken definitively from the Roman Catholic Church and converted to Lutheranism. Despite this, Tycho received a traditional education in accord with the Aristotelian beliefs which still prevailed in Denmark.
The opening sentence of this paragraph is complete codswallop. Tycho’s education appears to have been managed by his foster mother Inger Oxe, an intelligent woman of intellectual interests and capabilities and above all her elder brother, Tycho’s foster uncle, Peder Oxe a man of great intellect, who spoke several languages fluently, and who, unusual for a Danish aristocrat, had spent five years studying at various European universities. From 1567, Tycho was just twenty-one, till his death in 1575, Peder Oxe was Lord High Steward of Denmark and the most powerful man in the country. He did much to facilitate Tycho’s career, pulling strings in the background to help his foster nephew. Peder Oxe does not feature at all in Strathern’s account of Tycho’s life, a serious omission.
Tycho attended grammar school, where he learnt Latin, from the age of seven to twelve when he then entered Copenhagen University as Strathern, for once, correctly notes. At grammar school he would have lived in the house of the bishop, and at university in the house of a professor. His interest in mathematics began at university.
The following year, the adolescent Tycho witnessed a partial eclipse of the sun. Although this eclipse arrived a day after it had been predicted, the very fact of its prediction was what most impressed Tycho. Here at last he had a glimpse of something certain in his life. He immediately began purchasing books on astronomy, including one by Regiomontanus, a map of the constellations drawn by Dürer and De Sphaera Mundi (The Sphere of the World) written by the thirteenth-century monastic scholar Johannes de Sacrobosco, which was regarded as the classic exposition of the Ptolemaic earth-centred astronomical system.
He bought the Sacrobosco, a very elementary text, in 1560. In 1561 he bought the much more advance Comographia of Peter Apian and Regiomontanus’ Trigonometry. He didn’t acquire the Dürer star map until 1562, when he was in Leipzig, where he also acquired several other astronomy and astrology texts.
Subsequently, Uncle Jørgen despatched the fifteen-year-old Tycho on a tour of German universities, accompanied by a nineteen-year-old tutor who was instructed to cure him of this astronomy nonsense and make sure he equipped himself with the type of education expected of a court counsellor. Within months the young Tycho’s enthusiasm had convinced his tutor to disobey his instructions, and together the two of them embarked upon the study of astronomy at the safe distance of the University of Leipzig.
Normally, at the age of fifteen, a young aristocrat would be sent to live on the court of another aristocrat to train as a page, the first step towards becoming part of the ruling classes. That Tycho instead was sent on a tour of European universities was certainly due to his foster mother and foster uncle and not his foster father. His tutor was Anders Sørensen Vedel. Although Tycho began to study astronomy seriously in Leipzig he was not joined in this endeavour by Vedel, who, did however, admit defeat in his attempts to get Tycho to concentrate on his university studies.
Here [University of Leipzig] Brahe gained a thorough knowledge of both the Ptolemaic and the Copernican systems. Together, he and his tutor observed a close conjunction of the planets Jupiter and Saturn. Brahe was perplexed to discover that the tables drawn up using both the Ptolemaic system and the Copernican system contained minor inaccuracies in their predictions of the conjunction. This led him to start making astronomical observations of his own.
Tycho had begun making his own observation well before he observed the great conjunction and had already discovered the discrepancies in both the Ptolemaic and the Copernican tables.
He decided that the only way to create correct tables was to make meticulous personal observations, night after night, using the most accurate astronomical instruments available. (The telescope had yet to be invented.)
The only instrument that Tycho had available, at that time, was a cross-staff, that he had purchased, and which proved to be not particularly accurate.
Tycho returned to Denmark in 1565 at the age of eighteen.
[…]
Jørgen heroically dived into the canal and rescued the king, but unfortunately died some days later of pneumonia.
The bit I left out is not particularly important, but Strathern now continues:
Using the inheritance he received from his stepfather, Brahe set off to study at the historic University of Rostock, on the north German coast of the Baltic.
Jørgen had been intending to draw up his will naming Tycho his heir, but he died before he could do so, as Tycho was not legally his son he, in fact, inherited nothing. He was now depended for money on his father, Otte, who following the death of Jørgen, had taken over the supervision of his son, who was still a minor.
Here Brahe became involved in an altercation with a Danish cousin who was also studying at the university. Their dispute originated over which of them was the finest mathematician. However, rather than settle this in the obvious mathematical manner, the two of them ended up having a duel. It was during the course of this that Brahe lost his nose, which was sliced off at the bridge by his opponent’s sword.
The duel was not about who was the finest mathematician; this is a myth that was created by Pierre Gassendi (1592–1655) in his biography of Tycho written long after Tycho’s death. At the time Denmark was still effectively a feudal state dominated by a warrior cast. All young aristocrats carried a sword and were trained in the use of them. Duels between them were common and often led to serious injury and even death.
Brahe would continue with his studies at various German universities until he was twenty-six years old, by which time he had accumulated a superb collection of observational instruments – including ‘a large quadrant of brass and oak, thirty-eight feet in diameter and turned by four handles’. This enabled him to measure with precision the angle of elevation of a star above the horizon.
Tycho returned to Denmark in December 1570, just twenty-four years old. At that point in his life, he had a very small collection of fairly inaccurate astronomical instruments. The large oak and brass quadrant that Strathern references was designed and built by Tycho on the estate of the astronomer Paul Hainzel (1527–1581) in Augsburg in March 1570, the arc of the quadrant was 78 feet long. Tycho made observation with it for about six weeks in April and May of that year. It required forty men to erect it, so he certainly didn’t take it home with him. Given its bulk and extreme weight, Thoren’s thinks it was very difficult to operate and therefore not particularly accurate.
Next up:
Brahe was the first to insist upon the central importance of precise astronomical observation.* As recognized by the twentieth-century American philosopher of science E. A. Burtt, Brahe was ‘the first competent mind in modern astronomy to feel ardently the passion for exact empirical facts’. It was this empiricism, and his reliance upon mathematical calculation, which makes him a truly modern scientist – one of the first to emerge in the Renaissance era. Not until the third decade of the ensuing century would Galileo famously proclaim: ‘The book of nature is written in the language of mathematics.’ Brahe may not have said this, and he certainly would not have fully realized its implications, but his practice undeniably chimed with Galileo’s later remark.
I feel that both Regiomontanus and Wilhelm IV of Hessen-Kassel would feel deeply insulted by this paragraph. In 1471, Regiomontanus moved to Nürnberg explicitly to carry out a major programme of accurate astronomical observations to replace the data from the ancient Greeks that had become corrupted through multiple copying over the centuries. Sadly, he died before he could really get his programme started. Wilhelm IV set up an observatory in his castle beginning in 1560, so well before Tycho, with the same aim. He was instrumental in helping Tycho along his path and, as noted about, recommended to Frederick that he should give Tycho an observatory. Wilhelm and Tycho cooperated over the decades and Wilhelm’s observations were as accurate as Tycho’s. In terms of Galileo’s ‘The book of nature is written in the language of mathematics,’ I have pointed out often in the past this was old hat when Galileo wrote it, for example Robert Grosseteste said almost the same in the thirteenth century.
The footnote attached to this paragraph is hilarious:
* As Arthur Koestler pointed out, during the course of his life Copernicus would just make twenty-seven astronomical observations. The remainder of his astronomical data was reliant upon observations made by the likes of Ptolemy and Hipparchus in the second century AD. [my emphasis]
Ptolemy did indeed live in the second century AD, but Hipparchus lived in the second century BC!
Strathern now covers Tycho’s move, in 1570, to Herrevad Abbey with his Uncle Steen Bille, where they set up a laboratory, a glass works and a paper mill. He then writes:
Despite such distractions, Brahe was able to continue with his unrelenting schedule of nightly observations.
What Strathern neglects to mention is that the chief attraction of Herrevad Abbey, for Tycho, was that he and his uncle had also set up an observatory, so astronomical observations were his principal activity.
We then get the story of the 1572 nova and Tycho’s book De Stella Nova (About the New Star), which did indeed establish his reputation as an astronomer. However, Strathern goes over the top with his purple prose:
The publication of this work would make Brahe’s name known in universities throughout Europe. He had done for the universe something similar to what Copernicus had done for the Ptolemaic geocentric solar system. Astronomy was now a new science, released from the constrictions of a false Aristotelian orthodoxy [my emphasis]. Brahe was invited on a tour of European universities, and the metal-nosed Danish wonder with the huge, drooping, sausage-like moustache delivered lectures in halls from Heidelberg to Basel, and even as far afield as Venice, where he prolonged his stay for some weeks.
The sentence in bold is complete and utter twaddle. Although the observation of the nova, and Tycho was not the only astronomer to determine that it was supralunar, had an impact on Aristotelian cosmology, it is in no way comparable to Copernicus’ introduction of heliocentric astronomy. Note I use the word cosmology, whereas Strathern writes incorrectly astronomy. There is a major difference between astronomy and cosmology and I’m not even sure that Strathern knows the difference. The Aristotelian cosmological postulate that the heavens were incorruptible had already been seriously question in the sixteenth century by those observing the comets of the 1530s. This was why every astronomer in Europe, and not just Tycho, very actively observed the comet of 1577, to determine whether it was sub- or supralunar. The scientific status of astronomy was in no way changed by the nova of 1572.
Tycho was not invited on a tour of the European universities, another one of Strathern’s fantasies. His father having died in 1571 and his testament finally having been settled in 1574 with Tycho receiving his share, he was now a wealthy man. In March 1575, he went on a full-blown aristocratic peregrination during which he visited friends and fellow astronomers, it was on this journey that he met Wilhelm IV of Hessen-Kassel for the first time, which led to Wilhelm suggesting that Frederick give Tycho an observatory. He visited many towns in Germany but also Basel and Venice, where he did stay for a couple of weeks chatting to the local intelligentsia.
Brahe took up the king’s offer, and was soon at work constructing a large castle on Hven. In this he was inspired by the Italian Renaissance architect Andrea Palladio, with whose work he had been favourably impressed during his stay in Venice. Palladio’s villas sought to emulate the work of Ancient Greek and Roman architects, notably Vitruvius.
Nothing to complain about here, there is of course a footnote to Vitruvius referring to Leonardo’s Vitruvian Man, without noting its general importance amongst Renaissance artist-engineers. But the next paragraph starts once again with a stunner:
Brahe’s castle was named Uraniborg after Urania, the ancient classical muse of astronomy, mathematics and the exact sciences. The islanders were conscripted as building labourers, and 100 students were brought on board – to learn from the master, as well as assist him in his building project. Uraniborg was soon envisaged as far more than a castle, or even a scientific laboratory (though it would fulfil both these purposes); it was to be a Renaissance palace, fit for entertaining visiting scholars from all over Europe.
Urania was in Greek mythology the muse of astronomy. Urania is the goddess of astronomy and stars and has nothing to do with mathematics and the exact sciences, both terms being completely alien to Greek mythology. When I read about the 100 students drafted in to assist in building Uraniborg, I thought WHAT! Where did Strathern dredge that one up? Approximately one hundred was the number of students and assistant who worked on Hven, in the twenty-one years that it was in operation. Next paragraph, next blunder:
But this was not all. Quite apart from the castle, Brahe was determined to build himself the finest observatory in Europe [my emphasis]. This Stjerneborg (City of the Stars) would be constructed in the grounds of the castle, and would consist of no less than six chambers, placed underground so as ‘not to be exposed to the disturbing influence of the wind’.
Uraniborg was built primarily and principally as an observatory. The towers on either side of the building were observation platforms and the large mural quadrant that features in so many articles about Tycho ran through the very centre of the building.
Stjerneborg was a secondary observatory built after the fact for a number of reasons. Later, when both observatories were in operation, they would observe fully independently of each other and then Tycho would compare the results obtained. The “no less than six chambers” makes it sound enormous, but they were in fact all very small.
Strathern continues:
Such was the cost of Brahe’s project on Hven that Frederick II was soon diverting no less than 1 per cent of the entire national budget in order to keep it going, while many of the students and all of the locals were declared ‘indentured’ labour, i.e. unpaid.
The often repeated “1 percent” of crown revenues that flowed to Hven is misleading. Denmark was an oligarchy. Through his father and his foster father’s family, his mother’s family, and his foster mother’s family, Tycho belong to the upper one percent of the population. If he, as would have been expected of him, with his obvious intelligence and organisational talents, had taken up a political role, his share of the crown revenues would certainly have been more than one percent.
Nobody was declared ‘indentured’ labour. Hven was Tycho’s fiefdom and under Danish law, each farm on Hven was required to provide him with two man-day-labour a week, irrespective of the type of labour. The students who came to Hven over the years, did not work on the construction site but in the observatories. In exchange for their labour, they received free board and lodging as well as an on hands education in observational astronomy.
We then get the usual stories of royal visits, banquets at Uraniborg, and Tycho’s dwarf, Jepp. Strathern then delivers his usual presentist disapproval:
As we have already seen, Brahe remained susceptible to the scientific misapprehensions of his age. (The basement of Uraniborg also contained a number of furnaces, which were used for alchemy.)
The basement of Uraniborg was a purpose-built alchemical laboratory that was principally used to produce Paracelsian medicine, with which Tycho treated the inhabitants of his astronomical kingdom. Tycho was a close friend of Peder Sørensen (1542–1602), widely known by his Latinized name, Petrus Severinus, one of Europe’s leading Paracelsian physicians and personal physician to the king.
We finally get some more astronomy:
It was during these years that Brahe observed the Great Comet which was visible throughout Europe from November 1577 to January 1578. Brahe managed to calculate the distance of this comet from earth, and also its direction of flight. He was thus able to show that its orbit lay far beyond that of the moon. This disproved once and for all the Aristotelian contention that all stars beyond the moon were ‘immutable and eternal’.
As already mentioned above the central debate as to whether comets were sub- or supralunar had been raging in astronomical circles in the comets of the 1530s and that is why astronomers throughout Europe, and not just Tycho, very carefully observed the comet of 1577. Brahe did not calculate its distance from the Earth, but did, like several others, determine that it displayed no parallax and was therefore supralunar.
Tycho’s elk, which Strathern calls a Moose, falls down the stairs and Tycho’s sister, Sophie Brahe, gets an inaccurate nod:
Yet amidst all this, Brahe continued with his dogged research into what was indisputably genuine science. His meticulous map of the night sky had now progressed well beyond 500 stars. In this he was aided by his students, as well as his long-time assistant Sophie, his younger sister, who since the age of fourteen had clocked up a series of remarkable triumphs. These included a precise observation of the eclipse of the moon, as well as many adjustments to the Copernican tables.
There is no indication in Strathern’s narrative when exactly Tycho had succeeded in mapping 500 stars, but it would have been well into the 1580s. However, he places this next to his brief comment about Sophie Brahe. Sophie assisted Tyco in his observations of the lunar eclipse of 1573. This, observation, took place in Knutstorp Castle, the Brahe family seat, and not Uraniborg, which was not even a distant dream then. In Uraniborg, Sophie’s principal functions, on her visits, were acting as a host for aristocratic and royal visitors, a role Tycho’s common law wife could not fulfil and she was probably also, as a horticulturalist, responsible for the extensive herb garden and involved in the production of medicine, being like her brother a Paracelsian alchemist.
Up next is a long paragraph on the legendary accuracy of Tycho’s observations that end thus:
Such was the accuracy of Brahe’s observations of the motion of the sun that he was able to calculate the length of a year to within less than a second. As a result, Brahe’s readings would play a decisive role in the reformation of the calendar which took place under Pope Gregory XIII in 1582.
The Papal bull, Inter gravissimas, announcing the advent of the Gregorian calendar was issued on 24 February 1582. Tycho started building Uraniborg in 1579 and it only became operational as an observatory in 1583. Even if the very first thing that Tycho had done was to determine the length of the year, it wasn’t, I see a “slight problem” here. The length of year based on Tycho’s observations, 365 solar days, 5 hours, 48 minutes, 45 seconds (365.24219 days), was first published by Johannes Kepler in the Rudolphine Tables in 1627! The mathematical model used for the Gregorian calendar was produced by Aloysius Lilius (c. 1510–1576), who used the length of the year from the Alfonsine Tables, 365 solar days 5 hours 49 minutes 16 seconds (≈ 365.24255 days). In fact, he only used the value to two sexagesimal fractions (that’s base sixty), as was general astronomical practice at the time, 356; 14, 33 days.
Next up more garbage:
On the other hand, Brahe’s observations did not prevent him from making certain mistakes. For instance, he concluded that the distance from the earth of the planet Saturn (the furthest known planet at the time) was 48 million miles. As Asimov observed, this ‘seemed an enormous distance for the astronomers of the age but was only one-eighteenth of the real figure’.
Determining the actual sizes of the known cosmos and the orbits of the planets was in fact extremely difficult. The problem was only solved with the first approximately accurate determination of the astronomical unit, the mean distance between the Earth and the Sun, in the 1770s.
Strathern displays his ignorance of the history of astronomy in his brief presentation of the Tychonic system:
Another oddity in Brahe’s thinking was his overall conception of the universe – the so-called Tychonic system. Although Brahe was well aware of the Copernican heliocentric system, he refused to jettison all the workings of the Ptolemaic geocentric system. His view of the universe was essentially a compromise between the two. For Brahe the earth remained at the centre of the universe. The sun and the moon circled the earth. However, all other planetary bodies revolved around the sun. This lopsided picture found little favour with either camp in the growing Copernican–Ptolemaic debate [my emphasis].
I get tired of having to write this, but the Tychonic geo-heliocentric model was the one favoured by the majority of European astronomers from around 1620 till around 1670!
We then get the death of Frederick and Tycho’s abandonment of Hven and his eventual invitation from Rudolf II to settle in Prague:
In 1599 Brahe accepted the invitation of the Holy Roman Emperor Rudolf II, and moved to Prague to take up the post of Imperial Court Astronomer. He was given a castle in which to set up an observatory, and a young German assistant named Johannes Kepler. Brahe gave Kepler access to his star catalogue, and together they began working on the planetary motions, with the aim of drawing up a complete chart of these.
Rudolf II did not give Tycho a young German assistant named Johannes Kepler! The very idea is totally absurd. Kepler came to Prague on his own volition in 1600 hoping to find employment with Tycho and to gain access to Tycho’s data to fine tune his Platonic solids model of the cosmos. Tycho did not give Kepler access to his star catalogue, believing that Nicolaus Reimers Baer (Ursus) (1551–1600) had plagiarised him, he feared that Kepler would do the same. In fact, the first task that Tycho gave Kepler was to write an essay proving that Ursus had plagiarised him. Kepler wrote his Apologia Tychonis contra ursum (A Defence of Tycho against Ursus), which, however, was first published in the nineteenth century, but is now regarded as an important contribution to the history and philosophy of science.[3] Following this, Tycho gave Kepler limited access to his data with the task of determining the orbit of Mars.
The misinformation continues:
Brahe was fifty-four years old and feared that he had not fully accomplished his life’s mission. His last words to Kepler were: ‘Let me not seem to have lived in vain.’ But already Brahe had justified himself. In the eyes of Asimov, and other historians, ‘the crowning act of [Brahe’s] life’ was placing his star catalogue into the hands of his young assistant Kepler [my emphasis]. By now this did indeed record the verified position of almost 1,000 stars. Using Brahe’s work, Kepler would lay the foundations for the seventeenth-century Scientific Revolution, which culminated in Newton’s law of universal gravitation.
Exactly that didn’t happen. Tycho’s data was his private property and at his death was inherited by his children including his daughter Elizabeth and her husband Frans Gansneb genaamd Tengnagel van de Camp. Kepler got physical possession of the data but legally could not use it. There followed long and weary negotiations between Kepler and Frans Tengnagel, who claimed that he intended to continue Tycho’s life’s work. However, Tengnagel was a diplomat and not an astronomer, so in the end a compromise was achieved. Kepler could retain the data and utilise it but any publications that resulted from it would have Tengnagel named as co-author! In the end Tengnagel contributed a preface to the Astronomia Nova.
We then get a potted biography of Kepler’s childhood. Followed by Strathern’s antipathy towards everything that he doesn’t consider to be science, which culminates with the following description of Harmonice Mundi:
Not for nothing would his most characteristic work be entitled Harmonice Mundi (The Harmony of the World), which sought to bridge what we – with hindsight – see as the chasm between his scientific and pseudo-scientific thought. Here Kepler referenced musical harmony – his ideas harking back to Pythagorean mysticism. According to these ancient ideas, the individual soul is attuned to the movements of the heavens, reacting to the light emanating from the planets ‘according to the angles they form with each other, and the geometrical harmonies or disharmonies that result’. This is compared with the way the ear hears harmonies in music, and the eye sees harmonies in colour: ‘The capacity of the soul to act as a cosmic resonator has a mystic and a causal aspect: on the one hand it affirms the soul’s affinity with the anima mundi [world spirit], on the other, it makes it subject to strictly mathematical laws.’
This is the worst description of the Pythagorean concept of the harmony of the spheres that I’ve ever read. I’ve written a whole blog post about the Harmonice Mundi, so I’m not going to repeat it here.
More biography, more falsehoods:
After excelling at school, Kepler gained a scholarship to attend the nearby University of Tübingen. Kepler had been a sickly child, and it was expected that he would enter the Church, as his physique was thought incapable of surviving a more strenuous occupation. At university, Kepler studied theology.
Kepler did not study theology, as I explained in another blog post. Briefly, his scholarship was for a course of studies created to train new teachers and parish priests in Protestant Württemberg to replace the previous Catholic ones. Württemberg had only converted to Lutheran Protestantism thirty-six years before Kepler was born.
Strathern:
Fortunately, during this period theology was so all-pervasive that it included what we would call philosophy. And in doing so, it also included natural philosophy or science. All this was comprehended in the study of Aristotle – the most wide-ranging of the ancient philosophers. Aristotle’s theology predated Christianity; but as we have seen, over time this had been skilfully elided to enable his natural philosophy to become that most unscientific of entities – namely, the Holy Writ.
This is a constantly repeated claim of Strathern’s but no matter how oft he repeats it Aristotelian natural philosophy was never Holy writ. I’m still trying to imagine what Strathern thinks Aristotle’s theology was.
One step backwards, one step forwards: at Tübingen Kepler also embraced the Copernican view of the universe, yet with an unusual mystical twist. In student debate, ‘he defended heliocentrism from both a theoretical and theological perspective, maintaining that the Sun was the principal source of motive power in the universe’.
Strathern very obviously doesn’t realise that Kepler’s “the Sun was the principal source of motive power in the universe”, was in the context of the times a major step towards a theory of gravity.
Kepler would not finish his studies at Tübingen.
Yes, he did, see my blog post.
Possibly due to financial constraints, during his last year he accepted a post as a teacher of mathematics and astronomy at the Protestant school in Graz (in modern-day Austria). Here he continued to develop his mystic-scientific ideas along Aristotelian lines of teleology: the idea that everything in the universe has been created according to a divine purpose.
Kepler was sent to Graz as maths teacher at the Protestant school, and district mathematicus, as a condition of his scholarship, he would have preferred a position as a parish priest and only took up the post under protest. Kepler’s God was a mathematician and his philosophy of science was very definitely Platonic and not Aristotelian. Strathern obviously thinks that Aristotle’s philosophy was the only other thing around apart from modern science at the end of the sixteenth beginning of the seventeenth centuries. He apparently knows nothing about the revivals of Platonic, Stoic, and Archimedean philosophies, to say nothing of hermeticism, which are an important element of what we call the Renaissance.
One day while teaching at Graz, Kepler experienced a sudden insight into his understanding of the cosmos. He saw the sun as the centre of the solar system, with each of the planets orbiting about it according to a complex mathematical system. This involved an ingenious nesting of the five platonic solids, one within the other. Each of these solids was encased within a sphere, and these expanding spheres described the circular orbits of the planets about the sun. Though based on Greek mathematics, this shows a medieval ingenuity in its abstraction and symbolism. However, empirical science it is not.
This is a truly terrible description of how Kepler came to develop his geometrical model of the cosmos and I can’t be bothered to write the two-thousand-word essay needed to disentangle it; just accept it’s crap. I have a more accurate account here.
Kepler would publish these ideas in his first work, which he characteristically entitled Mysterium Cosmographicum (loosely, The Mystery of the Cosmos). This again has a distinctly medieval resonance: the Renaissance was very much an age of de-mystifying [my emphasis].
The Renaissance is the golden age of European alchemy, the golden age of European astrology, the age of astro-medicine as mainstream medicine, and the age of hermeticism not really “an age of de-mystifying.”
On the other hand, Kepler’s work was undoubtedly revolutionary – making, as it did, a strong contribution to the advancement of science. This was indeed the first work which publicly endorsed the Copernican heliocentric system [my emphasis].
No, it wasn’t! Rheticus, Gemma Frisius, Thomas Harriot, Giordano Bruno, …
Despite his otherworldly views, Kepler was ambitious and determined that his work should be recognized. With this in mind he sent copies of his Mysterium to the finest astronomers he knew – including Galileo and Brahe.
He never sent a copy to Galileo, who he didn’t know and who wasn’t really an astronomer in 1596. Galileo became the recipient of two copies of the Mysterium Cosmographicum by accident, as I’ve documented here.
Brahe, on the other hand, recognized a kindred spirit. Although he dismissed Kepler’s Copernican view in favour of his own, he was sufficiently impressed to enter into a correspondence with Kepler. As a result, when Brahe arrived in Prague in 1599 he invited Kepler to visit him. By now Kepler’s Copernican views were beginning to attract the attention of the Catholic authorities of the Counter-Reformation, which was becoming a force to be reckoned with in Graz [my emphasis]. Kepler travelled to Prague and was more than pleased when Brahe offered him the post of his assistant, under the auspices of the Holy Roman Emperor Rudolf II.
In the 1590s Kepler’s Copernican views did not interest the authorities in any way. Ferdinand the Archduke of Austria decided to banish all the Protestants from Styria. They were offered the choice of conversion or banishment. In the first wave of bans Kepler, a Lutheran Protestant, was granted an exception because in his role as district mathematicus he had produced very impressive astrological prognostications. Later the Protestant school was closed, and it was obvious that Kepler wouldn’t get a new exception, so he was desperately looking for alternative employment. After Mästlin and Tübingen refused to help, he set off to Prague to ask Tycho for work. Tycho had indeed invited him to Prague, but he never saw the invitation as he was already on his way to Prague before it arrived in Graz.
We get a garbled and inaccurate account of the initial dispute between Tycho and Kepler and then we move onto Tycho’s death:
When Brahe died in 1601, Kepler was left to fulfil Brahe’s injunction that he had not ‘lived in vain’. Kepler would more than fulfil this. Brahe had specifically set him the task of calculating the orbit of Mars, using his observations. Kepler had bragged that he would complete this within a week. In the end it took him eight years of ceaseless calculation [my emphasis].
It’s two years less than the usual inaccurate ten years but it’s still not right. The calculations ‘only’ took six years and were anything but ceaseless, as Kepler did quite a lot of other things during those years e.g., his observation of and report on the nova from 1604 or his observations of Halley’s Comet in 1607 and the publication in 1604 of his Astronomiae Pars Optica.
Kepler continued in the employ of Rudolf II, painstakingly seeking to complete Brahe’s map of the stars.
No, he didn’t! He was a theoretical astronomer and not an observational astronomer. His eyesight had been damaged by a case of smallpox when he was four years old, so he didn’t seek to complete Brahe’s map of the stars, painstakingly or in any other way.
In 1611 Bohemian Protestants rose against Rudolf II, and he was forced to abdicate in favour of his brother Matthias. Both parties in the dispute turned to Kepler for astrological advice. He did his best to produce conciliatory interpretations of the movements of the heavens, but to no avail. Amidst the deteriorating situation Kepler and his family fled Prague. While travelling, his wife Barbara and three sons contracted smallpox. In the year that followed, Barbara and one of his sons died. Eventually Kepler returned to Austria, this time settling in Linz, where he would later remarry.
It was Rudolf’s brothers, Ernst, Maximillian and Matthias, all staunch Catholics, who led the rebellion against him. Barbara Kepler contracted Hungarian spotted fever, and their three sons’ smallpox whilst they were still in Prague, and one son, Friedrich 6, died there. Kepler travelled alone to Linz to secure a position as teacher and district mathematicus. On his return to Prague, Barbara died, and he remained in the city until Rudolf died in early 1612 and Matthias became Holy Roman Emperor. Matthias re-affirmed Kepler’s position (and salary) as imperial mathematicus but allowed him to move to Linz.
Despite his troubles, Kepler persisted with his astronomical work, completing Brahe’s catalogue of the stars, along with his own additions, in 1617. Owing to the political situation it would be another ten years before it was published as the Rudolphine Tables, named after his former benefactor Rudolf II.
Kepler added nothing to Tycho’s star catalogue. He completed the Rudolphine Tables in 1623 and they were printed in 1627.
Despite the advent of the telescope, these would become the standard work of reference for many decades to come. Despite their differences, Kepler and Galileo would continue to correspond on surprisingly amicable terms. Galileo even sent Kepler one of his telescopes. This enabled Kepler to see for himself the moons of Jupiter, whose existence he had previously dismissed.
We unpack this backwards. Kepler never dismissed the existence of the Moons of Jupiter, rather he sat down and wrote an enthusiastic book praising Galileo’s telescopic discoveries, sight unseen, his Dissertatio cum Nuncio Sidereo (Conversation with the Starry Messenger) (1610). He sent a copy to Galileo in Padua, who had a new edition printed and published there, without asking Kepler’s permission or even informing him of what he had done.
Their very limited correspondence was seldom amicable. Galileo never sent Kepler a telescope, he regarded him as far too lowly and lacking in influence to be worth one of his telescopes, but he sent one to the Venetian ambassador in Prague with a request that Kepler be allowed to use it. The Rudolphine Tables remained the standard work of reference for decades because even with telescopes it would take decades before astronomers could make the necessary new observation needed to replace them. It took John Flamsteed (1646–1719) more than forty years to produce the next star catalogue and tables that replaced the Rudolphine Tables.
His knowledge of optics even enabled him to make considerable improvements to Galileo’s telescope, introducing two convex lenses, which were capable of higher magnification than Galileo’s combination of convex and concave lenses.
Strathern makes it seem that Kepler was a telescope builder, he wasn’t. In 1611, he published his Dioptrice, building on his Astronomiae Pars Optica from 1604, in which he explained the optics of the Dutch or Galilean telescope, a necessary step to the acceptance of the validity of the telescopic observations and discovery being made by Galileo and others. The book goes on to explain the optics of the astronomical telescope, two convex lenses, which took a long time to become accepted because it produced an inverted image and also because Galileo dismissed it. He also described the optics of the terrestrial telescope, like the astronomical telescope but with a third lens to invert the image and, last but not least, the telephoto lens. Galileo dismissed this milestone in the history of optics, as unreadable.
Kepler continued with his observations of the planets, and his calculations enabled him to predict that the planets Venus and Mercury would pass across the sun and be visible from earth as they made this ‘transit’. Kepler died in 1630 at the age of fifty-eight, while travelling back through Germany. The following year the first ‘transit’ of Mercury across the face of the sun was observed, just as Kepler had predicted.
Kepler made no observations of the planets, his ephemerides, tables of the planetary positions, were based entirely on the Rudolphine Tables. He didn’t predict the existence of transits of Mercury and Venus, that they would take place was fairly obvious after the discovery of the phases of Venus by various observers between 1610 and 1613. His ephemerides merely stated when they should occur. Pierre Gassendi (1592–1655) did in fact make the first telescopic observation of a transit of Mercury on 7 November 1631. The first transit of Venus was observed by Jeremiah Horrocks and William Crabtree on 24 November 1639; a transit that Horrocks had calculate himself, which was not in Kepler’s ephemerides.
Kepler’s legacy is difficult to underestimate. Despite his mystical inclinations, his mathematical descriptions of the solar system were novel, revolutionary in scope, and precise. Such innovations proved so difficult to accept, let alone understand, that many astronomers refused to accept his elliptical-orbit version of the Copernican solar system, with the planets altering speed as they swept through their orbits. But the confirmation in 1631 of his prediction of the transit of Mercury would prove a tipping point. Kepler’s laws of planetary motion would lead directly to Newton’s law of universal gravitation, which he formulated just thirty-five years after Kepler’s death.
Kepler’s first law was accepted relatively quickly, as was the third law, which however remained largely ignored for several decades. There was much discussion of his second law, his own proof of which was to say the least suspect, with various astronomers trying to find a better one. This debate played a significant role in the final acceptance of Kepler’s model of the solar system. What also played a significant role was his work on comets De cometis libelli tres I. astronomicus, theoremata continens de motu cometarum … II. physicus, continens physiologiam cometarum novam … III. astrologicus, de significationibus cometarum annorum 1607 et 1618 / autore Iohanne Keplero … published in 1619, and which was much consulted during the wave of comets in the 1660s. Strathern doesn’t mention this work at all. The confirmation in 1631 of his prediction of the transit of Mercury was not a tipping point for the Keplerian system. It was a confirmation of the accuracy of the Rudolphine Tables and of the fact that Mercury orbited the Sun, which had been tacitly assumed since the first telescopic observations of the phases of Venus. But, as I get tired of repeating, this fitted into any Tychonic or semi-Tychonic geo-heliocentric model; the most widely accepted solution at the time, which, as we saw above, Strathern dismisses out of hand. The statement that ‘Kepler’s laws of planetary motion would lead directly to Newton’s law of universal gravitation,’ is simply factually false. Newton would go on to prove the law of universal gravitation using Kepler’s laws, but they didn’t lead him to it. Also, Newton didn’t form the law of universal gravitation, which wasn’t ‘his’, thirty-five years after Kepler’s death, i.e., in 1665, Strathern is obviously here buying into the myth of the Annus mirabilis. As a last comment, Strathern also completely ignores Kepler’s role in the founding of modern optics, at least as important as his work in astronomy.
Like all the preceding chapters that I have reviewed from this book, this final chapter on Tycho and Kepler maintains a standard of scholarship that is so low that to use the word scholarship at all is to misuse it. The history of science chapters of Strathern book are a badly thrown together collection of factual errors, misinformation, myths, straight forward falsehoods, and indescribable garbage. That a serious publisher brought this rubbish onto the book market in a thought crime, and it should be removed and pulped immediately.
[1] Victor E. Thoren with contributions by John R. Christianson, The Lord of Uraniborg: A Biography of Tycho Brahe, CUP, 1990, p. 103 The Thoren’s Tycho biography is a masterpiece but of course Stratern didn’t consult it!
[2] Thoren p. 4
[3] See, Nicholas Jardine, The Birth of History and Philosophy of Science (CUP, 2nd rev. ed. 1988)