But the printer at Ulm turned out a disappointment. There were quarrels from the start, and later on threats of a lawsuit. At one point, Kepler even left Ulm in a sudden huff to find a better printer – in Tuebingen, of course. He travelled on foot, because he again suffered from boils on his backside, which made riding a horse too painful. The time was February, and Kepler was fifty-six. In the village of Blaubeuren, having walked fifteen miles, he turned back and made peace with the printer (whose name was Jonas Saur, meaning sour).
Seven months later, in September 1627, the work was at long last completed. It was just in time for the annual book mart at the Frankfurt Fair. Kepler, who had bought the paper, cast some of the type, acted as printer's foreman, and paid for the whole enterprise, now travelled himself to Frankfurt, with part of the first edition of a thousand copies, to arrange for its sale. It was truly a one-man show.
The last of the Egyptian plagues he had to contend with were Tycho's heirs, who now reappeared on the scene. The Junker Tengnagel had died five years before, but George de Brahe, the misfired "Tychonides", had continued the guerilla warfare against Kepler through all these years. He understood nothing of the contents of the work, but he objected to the fact that Kepler's preface occupied more space than his own, and to Kepler's remark that he had improved Tycho's observations, which he regarded as a slur on his father's honour. Since the work could not be published without the heirs' consent, the first two sheets, containing the dedications and prefaces, had to be reprinted twice; as a result, there exist three different versions among the surviving copies of the book.
The Tabulae Rudolphinae remained, for more than a century, an indispensable tool for the study of the skies – both planets and fixed stars. The bulk of the work consists of the tables and rules for predicting the positions of the planets, and of Tycho's catalogue of 777 star places, enlarged by Kepler to 1,005. There are also refraction-tables and logarithms, 5 put for the first time to astronomic uses; and a gazetteer of the towns of the world, their longitudes referred to Tycho's Greenwich – the meridian of Uraniborg on Hveen.
The frontispiece, designed by Kepler's hand, shows a Greek temple, under the columns of which five astronomers are engaged in lively dispute: an ancient Babylonian, Hipparchus, Ptolemy, Canon Koppernigk and Tyge de Brahe. In a wall at the base of the temple, under the five immortals' feet, there is a small niche in which Kepler crouches at a rough-hewn working table, mournfully gazing at the onlooker, and to all intents like one of Snow-White's Seven Dwarfs. The table-cloth in front of him is covered with numbers, penned by a quill within reach of his hand, indicating the fact that he has no money to buy paper. Over the top of the dome-shaped roof hovers the Imperial Eagle, dropping gold ducats from its beak, a symbol of imperial largesse. Two of the ducats have landed on Kepler's table-cloth, and two more are falling through the air – a hopeful hint.
2. The Tension Snaps
The last three years of Kepler's life carry haunting echoes of the legend of the Wandering Jew. Quis locus eligendus, vastatus an vastandus? – "What place shall I choose, one that is destroyed, or one that is going to be destroyed?" 6 He had left Linz forever, and he was without a fixed domicile. Ulm was only a temporary station, for the duration of the printing. He was staying in a house that a friend had put at his disposal, and though it had been specially altered to accommodate Kepler's family, he did not have them with him. On the journey up the Danube from Linz, the river had started to freeze, and he had to continue by carriage, leaving Susanna and the children midways at Ratisbon. At least, that is the explanation he gave in a letter to a correspondent; but he stayed in Ulm nearly ten months, and did not send for them.
This episode is characteristic of a certain oddness in his behaviour towards the end. It looks as if the heritage of his vagrant father and uncles was reasserting itself in his late middle age. His restlessness had found an outlet in creative achievement; when he finished the Rudolphine Tables, the tension snapped, the current was cut off, and he seemed to be freewheeling in aimless circles, driven on by an evergrowing, overriding anxiety. He was again plagued by rashes and boils; he was afraid that he would die before the printing of the Tables was finished; and the future was a waste land of famine and despair.
And yet, in spite of the war, his plight was to a large part imaginary. He had been offered the most coveted Chair in Italy, and Lord Bacon's envoy, Sir Henry Wotton, had invited him to England. * Yet he had refused:
"Am I to go overseas where Wotton invites me? I, a German? I who love the firm Continent and who shrink at the idea of an island in narrow boundaries of which I feel the dangers in advance?" 7
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*
Kepler had dedicated the Harmonice Mundi to James I.
After rejecting these tempting offers, he asked in despair his friend Bernegger in Strasburg whether he could get him a modest lectureship at that University. To attract an audience, he would be willing to cast the horoscope of every one of his hearers – because "the threatening attitude of the Emperor, which is apparent in all his words and deeds", left him with hardly any other hope. Bernegger wrote back that his town and University would welcome Kepler with open arms if he were to honour them with his presence, and offered him unlimited personal hospitality in his spacious house with its "very beautiful garden". But Kepler refused "because he could not afford the expense of the journey"; and when Bernegger tried to cheer him up with the news that a portrait of Kepler was hung on the wall of the University library: "everybody who visits the library sees it. If only they could see you in person!", Kepler's reaction was that the portrait "should be removed from that public place, the more so as it has hardly any likeness to myself." 8
3. Wallenstein
The Emperor's hostility, too, existed in Kepler's imagination only. In December 1617, Kepler left Ulm for Prague – having been almost constantly on the move since the Frankfurt Fair – and was received, to his surprise, as persona grata. The Court had returned to Prague for the coronation of the Emperor's son as King of Bohemia. Everybody was in high spirits: Wallenstein, the new Hannibal, had expelled the Danish invaders from Prussia; he had overrun Holstein, Schleswig and Jutland, and the enemies of the Empire were everywhere in retreat. Wallenstein himself had arrived in Prague a few weeks before Kepler; he was awarded, in addition to the Dutchy of Friedland which he already held, the Duchy of Sagan in Silesia.
The Emperor's Generalissimo and his Mathematicus had crossed each other's path before. Wallenstein was addicted to astrology. Twenty years earlier, in Prague, Kepler had been requested, by a go-between, to cast the nativity of a young nobleman who wished to remain unnamed. Kepler wrote a brilliant character-analysis of the future war leader, who was then twenty-five, which testifies to his psychological insight – for Kepler had guessed the identity of his anonymous client. * Sixteen years later, he was asked, again through a middle-man, to expand the horoscope – which Wallenstein had profusely annotated on the margin – this time without the pretence of anonymity. Kepler had again obliged, but had saved his face with the usual warnings against the abuses of astrology. This second horoscope, which dates from 1624, stops at 1634 with the prophecy that March will bring "dreadful disorders over the land": Wallenstein was murdered on 25 February of that year.†
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*
The name Wallenstein is written in Kepler's secret code on the original draft of the horoscope, which is still extant.
†
But ten years made a round figure at which even a well-paid-for horoscope could reasonably stop.
Thus the ground was prepared for their meeting amidst the celebrations at Prague. The meeting ended, after lengthy negotiations, with Kepler's appointment as Wallenstein's private mathematicus in his newly acquired Duchy of Sagan. The Emperor had no objection, and Kepler was allowed to retain his title as Imperial Mathematician for what it was worth ?
?? in terms of hard cash certainly not much; for the Crown's debts to Kepler in arrears of salary and gratuities by now amounted to 11,817 florins. The Emperor politely informed Wallenstein that he expected the latter to pay this sum – which Wallenstein, of course, never did.
The deal with Wallenstein concluded, both men left Prague in May 1628: Wallenstein to lay unsuccessful siege to Strahlsund, which was the beginning of his downfall; Kepler to visit his wife and children who were still in Ratisbon. He travelled on to Linz, to liquidate his affairs, then back to Prague, where his family joined him, and in July arrived with them in Sagan. But a considerable part of his possessions, including books and instruments needed for his work, he left behind in storage. It was the half-hearted move of an already broken man, whose behaviour became more and more erratic and devious.
Compared to Sagan, Linz had been paradise:
"I am a guest and a stranger here, almost completely unknown, and I hardly understand the dialect of the locals, who in turn consider me a barbarian... 9
I feel confined by loneliness, far away from the great cities of the Empire; where letters come and go slowly, and at heavy expense. Add to this the agitations of the [counter-] reformation which, though I am not personally hit, did not leave me untouched. Sad examples are before me, or before my mind's eye, of acquaintances, friends, people of my immediate neighbourhood being ruined, and conversation with the terror-stricken is cut off by fear...
A little prophetess of eleven in Kottbuss, which is between here and Frankfort-on-the-Oder, threatens with the end of the world. Her age, her childish ignorance and her enormous audiences make people believe in her." 10
It was the same story as in Gratz and Linz: the people were compelled to become Catholics, or to leave the country. They were not even allowed to follow a Lutheran hearse to the cemetery. The privileged position that Kepler enjoyed only intensified his loneliness. He was a prisoner of constant, nagging anxieties about matters large and small:
"It seems to me that there is disaster in the air. My agent Eckebrecht in Nuremburg, who handles all my affairs, has not written for two months... I am worried about everything, about my account in Linz, about the distribution of the Tables, about the nautical chart for which I have given a hundred and twenty florins to my agent, about my daughter, about you, about the friends in Ulm." 11
There was, of course, no printing press in Sagan, so he set out again on travels to procure type, machinery and printers. This took nearly eighteen months out of the altogether two years, the last of his life, that he spent in Sagan:
"Amidst the collapse of towns, provinces and countries, of old and new generations, in the fear of barbaric raids, of the violent destruction of hearth and home, I see myself obliged, a disciple of Mars though not a youthful one, to hire printers without betraying my fear. With the help of God I shall indeed bring this work to an end, in a soldierly fashion, giving my orders with bold defiance and leaving the worry about my funeral to the morrow." 12
4. Lunar Nightmare
When the new press was installed in December 1629, in Kepler's own lodgings, he embarked (with his assistant, Bartsch, whom Kepler had bullied into marrying his daughter Susanna) on a remunerative enterprise: the publication of ephemerides * for the years 1629-36. Ever since the Rudolphine Tables had come out, astronomers all over Europe were competing to publish ephemerides, and Kepler was anxious "to join the race" as he said, on the race track that he had built. But in between, he also began the printing of an old, favourite brain-child of his: Somnium – a dream of a journey to the moon. He had written it some twenty years before, and from time to time had added notes to it, until these had far outgrown the original text.
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*
"Ephemerides" provide detailed information about the motions of the planets for a given year, whereas "tables" give only the broad outlines on which the calculations are based.
The Somnium remained a fragment; Kepler died before he finished it, and it was only published posthumously, in 1634. It is the first work of science-fiction in the modern sense – as opposed to the conventional type of fantasy-utopias from Lucian to Campanella. Its influence on later authors of interplanetary journeys was considerable – from John Wilkins' Discovery of a New World and Henry More, right down to Samuel Butler, Jules Verne and H. G. Wells. 13
Somnium starts with a prelude full of autobiographical allusions. The boy Duracotus lived with his mother Fiolxhilda on Iceland "which the ancients called Thule". * The father had been a fisherman, who had died at the age of one hundred and fifty when the boy was only three. Fiolxhilda sold herbs in little bags of ram-skin to the seamen and conversed with demons. At fourteen, the boy curiously opened one of the little bags, whereupon his mother, in a fit of temper, sold him to a seafaring captain. The captain left him on the Isle of Hveen, where for the next five years Duracotus studied the science of astronomy under Tycho de Brahe. When he returned home, his repentant mother, as a treat, conjured up one of the friendly demons from Lavania † – the moon – in whose company selected mortals might travel to that planet. "After completing certain ceremonies, my mother, commanding silence with her outstretched hand, sat down beside me. No sooner had we, as arranged, covered our heads with a cloth, when a hoarse, supernatural voice began to whisper, in the Icelandic language, as follows..."
Thus ends the prelude. The journey itself, the demon explains, is only possible during an eclipse of the moon, and must therefore be completed in four hours. The traveller is propelled by the spirits, but he is subject to the laws of physics; it is at this point that science takes over from fantasy:
"The initial shock [of acceleration] is the worst part of it, for he is thrown upward as if by an explosion of gunpowder... Therefore he must be dazed by opiates ‡ beforehand; his limbs must be carefully protected so that they are not torn from him and the recoil is spread over all parts of his body. Then he will meet new difficulties: immense cold and inhibited respiration... When the first part of the journey is completed, it becomes easier because on such a long journey the body no doubt escapes the magnetic force of the earth and enters that of the moon, so that the latter gets the upper hand. At this point we set the travellers free and leave them to their own devices: like spiders they will stretch out and contract, and propel themselves forward by their own force – for, as the magnetic forces of the earth and moon both attract the body and hold it suspended, the effect is as if neither of them were attracting it – so that in the end its mass will by itself turn toward the moon."
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*
Kepler chose the name Duracotus because it sounded Scottish "and Scotland lies on the Islandic ocean"; "Fiolx" was the name for Iceland which he saw on an old map.
†
From Lavanah – the Hebrew name of the moon. (Lavan = white.)
‡
It has recently been suggested that space-travellers should be anaesthetized during the initial acceleration.
In the Astronomia Nova Kepler had come so close to the concept of universal gravity, that one had to assume the existence of a psychological blockage which made him reject it. In the passage just quoted he not only takes it for granted, but, with truly astonishing insight, postulates the existence of "zones of zero gravity" – that nightmare of science fiction. Later on in the Somnium he took a further step in the same direction by assuming that there are spring tides on the moon, due to the joint attraction of sun and earth.
The journey completed, Kepler proceeds to describe conditions on the moon. A lunar day, from sunrise to sunset, lasts approximately a fortnight, and so does a moon-night – for the moon takes a month to turn once round its axis, the same time it takes to complete a revolution round the earth. As a result, it turns always the same face to the earth, which t
he moon-creatures call their "volva" (from revolvere, to turn). This face of the moon they call the Subvolvan half, the other is the Prevolvan half. Common to both halves is that their year consists of twelve days-and-nights, and the resulting dreadful contrasts of temperature – scorching days, frozen nights. Common to both are also the queer motions of the starry sky – the sun and planets scuttle incessantly back and forth, a result of the moon's gyrations round the volva. This "lunatic" astronomy – in the legitimate double meaning of the word – which Kepler develops with his usual precision, is sheer delight; nobody before (nor since, as far as I know) had attempted such a thing. But when it comes to conditions on the moon itself, the picture becomes grim.
The Prevolvans are the worst off. Their long nights are not made tolerable by the presence of the huge volva, as on the other hemisphere, for the Prevolvans of course never see the earth.
Their nights are "bristling with ice and snow under the raging, icy winds." The day that follows is no better: for a fortnight the sun never leaves the sky, heating the air to a temperature "fifteen times hotter than our Africa".
The Subvolvans are a little better off because the huge volva softens their nights by reflecting some of the light and heat 14 of the sun. The volva's surface is fifteen times that of our moon, and it stays always in the same place on the sky "as if nailed on", but growing and waning from full-volva to new volva, as our moon. At full-volva, Africa appears as a human head severed at its shoulders; Europe, a girl in a long robe bends down to kiss it while her long arm, stretched backwards, lures a jumping cat towards her. *
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*
The back of the head is the Sudan, its chin Algeria; the girl's head is Spain, her open mouth at Malaga, her chin at Murcia; her arms are Italy and the British Isles, the latter luring the Scandinavian cat.