The Sleepwalkers

  Tycho's observatory, the Uraniburg, built by a German architect under Tycho's supervision, was a symbol of his character, in which meticulous precision combined with fantastic extravagance. It was a fortress-like monster which is said to have been "epoch-making in the history of Scandinavian architecture", but on the surviving woodcuts looks rather like a cross between the Palazzo Vecchio and the Kremlin, its Renaissance façade surmounted by an onion-shaped dome, flanked by cylindrical towers, each with a removable top housing Tycho's instruments, and surrounded by galleries with clocks, sundials, globes, and allegorical figures. In the basement were Tycho's private printing press, fed by his own paper mill, his alchemist's furnace and private prison for unruly tenants. He also had his own pharmacy, his game preserves and artificial fishponds; the only thing he was missing was his tame elk. It had been dispatched to him from his estate but never reached the island. While spending a night in transit at Landskroner Castle, the elk wandered up the stairs to an empty apartment where it drank so much strong beer that on its way downstairs it stumbled, broke its leg and died.

  In the library stood his largest celestial globe, five feet in diameter, made of brass, on which, in the course of twenty-five years, the fixed stars were engraved one by one, after their correct positions had been newly determined by Tycho and his assistants in the process of re-mapping the sky; it had cost five thousand dalers, the equivalent of eighty years of Kepler's salary. In the south-west study, the brass arc of Tycho's largest quadrant – fourteen feet in diameter – was fastened to the wall; the space inside the arc was filled with a mural depicting Tycho himself surrounded by his instruments. Later on, Tycho added to the Uraniburg a second observatory, the "Starburg", which was built entirely underground to protect the instruments from vibration and wind, only the dome-shaped roofs rising above ground level; so that "even from the bowels of the earth he could show the way to the stars and the glory of God". 7 Both buildings were full of gadgets and automata, including statues turning on hidden mechanisms, and a communication system that enabled him to ring a bell in the room of any of his assistants – which made his guests believe that he was convoking them by magic. The guests came in an unceasing procession, savants, courtiers, princes and royalty, including King James VI of Scotland.

  Life at Uraniburg was not exactly what one would expect to be the routine of a scholar's family, but rather that of a Renaissance court. There was a steady succession of banquets for distinguished visitors, presided over by the indefatigable, hard-drinking, gargantuan host, holding forth on the variations in the eccentricity of Mars, rubbing ointment on his silver nose, and throwing casual titbits to his fool Jepp, who sat at the master's feet under the table, chattering incessantly amidst the general noise. This Jepp was a dwarf, reputed to have second sight, of which he seemed to give spectacular proof on several occasions.

  Tycho is really a refreshing exception among the sombre, tortured, neurotic geniuses of science. He was, it is true, not a creative genius, only a giant of methodical observation. Still, he displayed all the vanity of genius in his interminable poetic outpourings. His poetry is even more dreadful than Canon Koppernigk's, and more abundant in quantity – Tycho was never in want of a publisher, since he had his own paper mill and printing press. Even so, his verses and epigrams overflowed onto the murals and ornaments of Uraniburg and Stjoerneburg, which abounded in mottoes, inscriptions and allegorical figures. The most impressive of these, adorning the wall of his chief study, represented the eight greatest astronomers in history, from Timocharis to Tycho himself, followed by "Tychonides", a yet unborn descendant – with a caption expressing the hope that he would be worthy of his great ancestor.

  4. Exile

  Tycho stuck it out on his Scarlet Island for twenty years; then, at fifty-one, he took up his wanderings again. But by that time the bulk of his life's work was done.

  In looking back at it, he divided his observations into "childish and doubtful ones" (during his student days at Leipzig), into "juvenile and habitually mediocre ones" (up to his arrival at Hveen), and into "virile, precise and absolutely certain ones" (made at the Uraniburg). 8 The Tychonic revolution in astronomical method consists in the previously unequalled precision and continuity of his observations. The second point is perhaps even more important than the first: one could almost say that Tycho's work compares with that of earlier astronomers, as a cinematographic record with a collection of still photographs.

  In addition to his remarkable survey of the solar system, his re-mapping of the firmament comprised a thousand fixed stars (of which the positions of 777 were determined accurately, and the remaining 223 places were hastily thrown in just before he left Uraniburg, to make up a round thousand). His proof that the nova of '72 was a true star and that the comet of '77 moved in an orbit far outside the moon's, disposed of the already shaken belief in the immutability of the skies and the solidity of the celestial spheres. Lastly, his system of the world, which he offered as an alternative to the Copernican, though without much scientific value, played, as we shall see, a historically important part. 8a

  The reasons which made Tycho abandon his island realm were of a rather sordid character. Tyge, the Scandinavian squire, was as high-handed in his dealings with men as he was humble towards scientific fact; as arrogant towards his like as he was delicate and tender in handling his instruments. He treated his tenants appallingly, extracting from them labour and goods to which he was not entitled, and imprisoning them when they demurred. He was rude to all who evoked his displeasure, including the young King, Christian IV. The good King Ferdinand had died in 1588 (of too much drink, as Vedel dutifully pointed out in his funeral oration) and his successor, though well disposed to Tycho, on whose sorcerer's island he had spent a delightful day as a boy, was unwilling to close his eyes to Tycho's scandalous rule of Hveen. By this time, Tycho's arrogance seemed to be verging on mania of grandeur. He left several letters of the young King unanswered, flaunted the decisions of the provincial courts, and even of the High Court of Justice, by holding a tenant and all his family in chains. As a result, the great man who had been Denmark's glory, became a personage thoroughly disliked throughout the country. No direct steps were taken against him, but his fantastic sinecures were reduced to more reasonable proportions, and this gave Tyge, who was becoming increasingly bored and restless on his Scarlet Island, the needed pretext to resume his wanderings again.

  He had been preparing his emigration for several years, and when he left Hveen around Easter 1597, he did it in his customary grandiose manner, travelling with a suite of twenty – family, assistants, servants, and the dwarf Jepp – his baggage comprising the printing press, library, furniture, and all the instruments (except the four largest, which followed later). Ever since, as a student, he had ordered his first quadrant at Augsburg, he had been careful to have all his instruments made in a way that they could be dismantled and transported. "An astronomer," he declared, "must be cosmopolitan because ignorant statesmen can not be expected to value their services." 9

  The first station of the Tychonic caravan was Copenhagen, the next Rostock from where, having left Danish territory, Tycho wrote a rather impertinent letter to King Christian, complaining about the treatment he had received from his ungrateful country, and declaring his intention "to look for help and assistance from other princes and potentates", yet graciously expressing his willingness to return "if it could be done on fair conditions and without injury to myself." Christian wrote back a remarkable letter which soberly refuted Tycho's complaints point by point, and made it clear that the condition of his return to Denmark was "to be respected by you in a different manner, if you are to find in us a gracious lord and King." 10

  For once Tyge had found his match. There were only two men in his life who got the better of him, King Christian of Denmark, and Johannes Kepler from Weil-der-Stadt.

  His bridges burnt, Tycho and his private circus continued their wanderings for another two years – to Wandsbeck Castle near H
amburg, to Dresden, to Wittenberg. Lastly, in June 1599, they arrived in – or rather made their entry into – Prague, residence of the Emperor Rudolph II, to whom, by the grace of God, Tycho de Brahe had been appointed Imperial Mathematicus. He was again to have a castle of his choice, and a salary of three thousand florins a year ( Kepler in Gratz had two hundred), in addition to some "uncertain income which might amount to some thousands". 11

  Had Tycho remained in Denmark, it is highly unlikely that Kepler could have afforded the expense to visit him during the short remaining span of Tycho's life. The circumstances which made them both exiles, and guided them towards their meeting, can be attributed to coincidence or providence, according to taste, unless one assumes the existence of some hidden law of gravity in History. After all, gravity in the physical sense is also merely a word for an unknown force acting at a distance.

  5. Prelude to the Meeting

  Before they met in the flesh at Benatek Castle, near Prague, Kepler and Tycho had been corresponding for two years.

  From the very beginning, the relationship had started on the wrong foot, owing to an innocent blunder which young Kepler committed. The episode involved Tycho's lifelong bitter enemy, Ursus the Bear, and makes the fathers of astronomy appear like actors in an opera buffo.

  Reymers Baer, * who came from Ditmar, had started as a swineherd, and ended up as Imperial Mathematicus – at which post Tycho was to succeed him, and Kepler was to succeed Tycho. To achieve, in the sixteenth century, such a career, certainly required considerable gifts – which, in Ursus, were combined with a dogged and ferocious character, always ready to crush his victims' bones in a bear-like hug. In his youth he had published a Latin grammar and a book on land surveying, then entered the service of a Danish nobleman called Erik Lange. In 1584, Lange visited Tycho at Uraniburg, and took Ursus with him. It must have been a rather hectic encounter, as will presently be seen.

  Four years after that visit, Ursus published his Fundaments of Astronomy 12 in which he explained his system of the universe.

  ____________________

  *

  German for bear, hence his latinized name, Ursus.

  It was, except for some details, the same system which Tycho had worked out in secret, but had not published yet, since he wanted more data to elaborate it. In both systems the earth was reinstated as the centre of the world, but the five planets were now circling round the sun and, with the sun, round the earth. 13 This was obviously a revival of the intermediary system between those of Herakleides and Aristarchus of Samos (see Fig. C, p. 46).

  Tycho's system was, therefore, by no means very original; but it had the advantage of a compromise between the Copernican universe and the traditional one. It automatically recommended itself to all those who were reluctant to antagonize academic science, and yet desirous to "save the phenomena", and was to play an important part in the Galileo controversy. Actually, the Tychonic system was "discovered" quite independently by yet a third scholar, Helisaeus Roeslin, as it so often happens with inventions that "lie in the air". But Tycho, who was as proud of his system as Kepler of his five perfect solids, was convinced that Ursus had stolen it, by snooping through his manuscripts during that visit in 1584. He collected evidence to prove that Ursus had been prying among his papers; that he had taken the precaution of letting his pupil Andreas share a room with Ursus; that while Ursus was asleep, the faithful pupil "had taken a handful of papers out of one of his breeches pockets, but was afraid to search the other pocket for fear of waking him"; and that Ursus, on discovering what had happened, "behaved like a maniac", whereupon all papers which did not concern Tycho were restored to him.

  According to Ursus, on the other hand, Tycho had been haughty and arrogant to him; had tried to shut him up by remarking that "all these German fellows are half-cracked"; and had been so suspicious about his observations "which he was able to take through his nose, without needing other sights" that he got somebody to search his, Ursus', papers the night before his departure.

  The long and short of it is that the Bear had probably been snooping among Tycho's observations, but there is no proof that he had stolen Tycho's "system", nor that there was any need for him to steal it.

  It was into this hornets' nest that young Kepler blundered, when he had just hit upon the idea of the Mysterium and felt the urgent need to share his joy with the whole world of learning. Ursus was then the Imperial Mathematicus at Prague; so Kepler dashed off a fan letter to him, starting in typical fan-mail style: "There exist curious men who, unknown, write letters to strangers in distant lands"; and continuing with Keplerian effusion that he was familiar "with the bright glory of thy fame which makes thee rank first among the mathematici of our time like the sun among the minor stars". 14

  This was written in November, 1595. The Bear never answered the unknown young enthusiast's letter; but two years later, when Kepler was already well known, Ursus printed the letter, without asking for Kepler's permission, in a book 15 in which he claimed the priority of the "Tychonic" system, and abused Tycho in most ferocious language. The book bore the motto "I will meet them [meaning Tycho and Co.] as a bear bereaved of her whelps – Hosiah 13 ". Thus Tycho, of course, got the impression that Kepler was siding with the Bear – which was precisely what the Bear had intended. The situation was all the more embarrassing for poor Kepler, as he had in the meantime also written a fan letter to Tycho, in which he called him "the prince of mathematicians not only of our time but of all times". 16 Moreover, unaware of the Homeric battle between the two, he had asked Ursus, of all people, to forward a copy of the Mysterium to Tycho!

  Tycho reacted with unusual diplomacy and restraint. He acknowledged Kepler's letter and book with great courtesy, praised him for the ingenuity of the Mysterium while expressing certain reserves, and expressed the hope that Kepler would now make an effort to apply his theory of the five solids to Tycho's own system of the universe. (Kepler wrote on the margin: "Everybody loves himself, but one can see his high opinion of my method.") 17 Only in a postscript did Tycho complain about Kepler's praise of Ursus. A little later Tycho wrote another letter to Maestlin, 18 in which he criticized Kepler's book much more severely, and repeated his complaint. The intention behind this was obvious: Tycho had immediately realized young Kepler's exceptional gifts, wanted to win him over to his side, and hoped that Maestlin would exert his authority with his former pupil in this sense. Maestlin duly transmitted Tycho's complaint to Kepler, who realized only now into what a frightful tangle he had got himself – and, of all people, with Tycho, who was his only hope. So he sat down and penned a long and agonized epistle to Tycho in true Keplerian style, bubbling with sincerity, cheating a little about the facts, pathetic and brilliant and slightly embarrassing, all at the same time:

  "How come? Why does he [ Ursus] set such value on my flatteries? ... If he were a man he would despise them, if he were wise he would not display them on the market place. The nonentity which I then was, searched for a famous man who would praise my new discovery. I begged him for a gift and behold, it was he who extorted a gift from the beggar ... My spirit was soaring and melting away with joy over the discovery I had just made. If, in the selfish desire to flatter him I blurted out words which exceeded my opinion of him, this is to be explained by the impulsiveness of youth." 19

  And so on. But there is one staggering admission in the letter: when Kepler read Ursus' Fundaments of Astronomy he had believed that the trigonometrical rules in it were Ursus' original discoveries and did not realize that most of them could be found in Euclid! 20 One feels the ring of truth in this admission of young Kepler's abysmal ignorance of mathematics at a time when, guided by intuition alone, he had mapped out the course of his later achievements in the Mysterium.

  Tycho replied briefly, and with a gracious condescension which must have been rather galling to Kepler, that he had not required such an elaborate apology. Thus the incident was patched up, though it kept rankling in Tycho who, later on, whe
n Kepler became his assistant, would force him to write a pamphlet In Defence of Tycho against Ursus – a chore which Kepler detested. But for the time being, Tycho was willing to forget the unfortunate episode, and anxious to get Kepler as his collaborator. He found it difficult to get the new observatory at Benatek Castle going, and his former assistants were in no hurry to rejoin the former despot of Hveen. So he wrote to Kepler in December 1599:

  "You have no doubt already been told that I have been most graciously called here by his Imperial Majesty and that I have been received in the most friendly and benevolent manner. I wish that you would come here, not forced by the adversity of fate, but rather on your own will and desire for common study. But whatever your reason, you will find in me your friend who will not deny you his advice and help in adversity, and will be ready with his help. But if you come soon we shall perhaps find ways and means so that you and your family shall be better looked after in future. Vale.

  Given at Benatek, or the Venice of Bohemia, on December 9, 1599, by your very sympathetic Tycho Brahe's own hand." 21

  But by the time this letter arrived in Gratz, Kepler was already on his way to Tycho.

  V TYCHO AND KEPLER

  1. The Gravity of Fate

  THE town and castle of Benatek were twenty-two miles, a six-hours' journey, to the north-east of Prague. They overlooked the river Iser, which often flooded the surrounding orchards, hence the name "Bohemian Venice". Tycho had selected Benatek among the three castles which the Emperor had offered for his choice – perhaps because the watery surroundings reminded him of Hveen. He had taken possession of the castle in August 1599 – six months before Kepler's arrival – and had started at once tearing down walls and erecting new ones, intending to build another Uraniburg, and announcing his intention in high-flung poems which were inscribed over the entrance of the future observatory. There was also to be a separate gate for the Emperor, who had reserved an adjoining building for his visits.