CHAPTER III.

_Kepler's continued Embarrassments--Death of Mathias--Liberality of Ferdinand--Kepler's "Harmonies of the World"--The Epitome of the Copernican Astronomy--It is prohibited by the Inquisition--Sir Henry Wotton, the British Ambassador, invites Kepler to England--He declines the Invitation--Neglect of Genius by the English Government--Trial of Kepler's Mother--Her final Acquittal--And Death at the age of Seventy-five--The States of Styria burn publicly Kepler's Calendar--He receives his Arrears of Salary from Ferdinand--The Rudolphine Tables published in 1628--He receives a Gold Chain from the Grand Dulce of Tuscany--He is Patronised by the Duke of Friedland--He removes to Sagan, in Silesia--Is appointed Professor of Mathematics at Rostoch--Goes to Ratisbon to receive his Arrears--His Death, Funeral, and Epitaph--Monument Erected to his Memory in 1803--His Family--His Posthumous Volume, entitled "The Dream, or Lunar Astronomy."_

Kepler was kept in a state of constant anxiety from the delay in the Government to pay up the arrears of his pension, while their repeated promises prevented him from accepting of other employments. He had hoped that the affair of the Bolognese chair would rouse the imperial treasury to a sense of its duty, and enable him to publish the Rudolphine Tables,--that great work which he owed to the memory both of Tycho and of Rudolph. But though he was disappointed in this expectation, an event now occurred which at least held out the prospect of a favourable change in his circumstances. The Emperor Mathias died in 1619, and was succeeded by Ferdinand III., who not only continued him in the situation of his principal mathematician, with his former pension, but promised to pay up the arrears of it, and to furnish the means for publishing the Rudolphine Tables.

The year 1619, so favourable to Kepler's prospects in life, was distinguished also by the publication, at Linz, of one of his most remarkable productions, entitled "The Harmonies of the World." It is dedicated to James I. of England, and will be for ever memorable in the history of science, as containing the celebrated law that the squares of the periodic times of the planets are to one another as the cubes of their distances. This singular volume, which is marked with all the peculiarities which distinguish his Cosmographical Mystery, is divided into five books. The two first books are principally geometrical, and relate to regular polygons inscribed in a circle; the third book is a treatise on music, in which musical proportions are derived from figures; the fourth book is astrological, and treats of the harmony of rays emanating on the earth from the heavenly bodies, and on their influence over the sublunary or human soul; the fifth book is astronomical and metaphysical, and treats of the exquisite harmonies of the celestial motions, and of the celebrated third law of the universe, which we have already referred to.

This law, as he himself informs us, first entered his mind on the 8th March 1618; but, having made an erroneous calculation, he was obliged to reject it. He resumed the subject on the 15th May; and having discovered his former error, he recognised with transport the absolute truth of a principle which for seventeen years had been the object of his incessant labours. The delight which this grand discovery gave him had no bounds. "Nothing holds me," says he; "I will indulge in my sacred fury; I will triumph over mankind by the honest confession, that I have stolen the golden vases of the Egyptians, to build up a tabernacle for my God, far away from the confines of Egypt. If you forgive me, I rejoice; if you are angry, I can bear it. The die is cast; the book is written, to be read either now or by posterity, I care not which. It may well wait a century for a reader, as God has waited six thousand years for an observer."

About the same time, in 1618, Kepler published, at Linz, the _three_ first books of his "Epitome of the Copernican Astronomy," of which the _fourth_ was published at the same place in 1622, and the _fifth_, _sixth_, and _seventh_ at Frankfort in the same year. This interesting work is a kind of summary of all his astronomical views, drawn up in the form of a dialogue for the perusal of general readers. Immediately after its publication, it was placed by the Inquisition in the list of prohibited books; and the moment Kepler learned this from his correspondent Remus, he was thrown into great alarm, and requested from him some information respecting the terms and consequences of the censure which was then pronounced against him. He was afraid that it might compromise his personal safety if he went to Italy; that he would be compelled to retract his opinions; that the censure might extend to Austria; that the sale of his work would be ruined; and that he must either abandon his country or his opinions.

The reply of his friend Remus calmed his agitated mind, by explaining to him the true nature of the prohibition; and he concluded his letter with a piece of seasonable exhortation, "There is no ground for your alarm either in Italy or in Austria, only keep yourself within bounds, and put a guard upon your own passions."

In the year 1620, Sir Henry Wotton, the English ambassador at Venice, paid a visit to Kepler on his way through Germany. It does not appear whether or not this visit was paid at the desire of James I., to whom Kepler had dedicated one of his works, but from the nature of the communication which was made to him by the ambassador, there are strong reasons to think that this was the case. Sir Henry Wotton urged Kepler to take up his residence in England, where he could assure him of a welcome and an honourable reception; but, notwithstanding the pecuniary difficulties in which he was then involved, he did not accept of the invitation. In referring to this offer in one of his letters, written a year after it was made, he thus balances the difficulties of the question--"The fires of civil war," says he, "are raging in Germany. Shall I then cross the sea whither Wotton invites me? I, a German, a lover of firm land, who dread the confinement of an island, who presage its dangers, and must drag along with me my little wife and flock of children?" As Kepler seems to have entertained no doubt of his being well provided for in England, it is the more probable that the British Sovereign had made him a distinct offer through his ambassador. A welcome and an honourable reception, in the ordinary sense of these terms, could not have supplied the wants of a starving astronomer, who was called upon to renounce a large though an ill-paid salary in his native land; and Kepler had experienced too deeply the faithlessness of royal pledges to trust his fortune to so vague an assurance as that which is implied in the language of the English ambassador. During the two centuries which have elapsed since this invitation was given to Kepler, there has been no reign during which the most illustrious foreigner could hope for pecuniary support, either from the Sovereign or the Government of England. What English science has never been able to command for her indigenous talent, was not likely to be proffered to foreign merit. The generous hearts of individual Englishmen, indeed, are always open to the claims of intellectual pre-eminence, and ever ready to welcome the stranger whom it adorns; but through the frozen life-blood of a British minister such sympathies have seldom vibrated; and, amid the struggles of faction and the anxieties of personal and family ambition, he has turned a deaf ear to the demands of genius, whether she appeared in the humble posture of a suppliant, or in the prouder attitude of a national benefactor.

If the imperial mathematician, therefore, had no other assurance of a comfortable home in England than that of Sir Henry Wotton, he acted a wise part in distrusting it; and we rejoice that the sacred name of Kepler was thus withheld from the long list of distinguished characters whom England has starved and dishonoured.

In the year 1620, Kepler was exposed to a severe calamity, which continued to harass him for some time. His mother, Catherine Kepler, to whose peculiarities of temper we have already referred, was arrested on the 5th April, upon a charge of a very serious nature. One of her friends having some years before suffered a miscarriage, was subsequently attacked with violent headaches, and Catherine was charged with having administered poison to her friend. This accusation was indignantly repelled, and a young doctor of the law, whom she consulted, advised her to raise an action against her calumniator. From professional reasons, or probably pecuniary ones, this zealous practitioner continued to delay the lawsuit for five years. The judge who tried it happened to be displaced, and was succeeded by another, who had a personal quarrel with the prosecutor. The defender, who was aware of this favourable change in her case, became the accuser, and, in July 1620, Catherine Kepler was sent to prison, and condemned to the torture. The moment this event reached the ears of her son, he quitted Linz, and arrived in time to save her from punishment. He found that the evidence upon which she was condemned had no other foundation but her own intemperate conduct; and, though his interference was successful, yet she was not finally released from prison till the 4th November 1621. Convinced of her innocence, this bold woman, now in the 79th year of her age, raised a new action for damages against her opponent; but her death, in April 1622, put an end to her own miseries, as well as to the anxiety of her son. Among the virtues of this singular woman, we must number that of generosity. Moestlin, the old preceptor of Kepler, had generously declined any compensation for his instructions. Kepler never forgot this act of kindness, and, in the midst of his poverty, he found means to send to Moestlin a handsome silver cup in token of his gratitude. In acknowledging this gift, Moestlin remarks, "Your mother had taken it into her head that you owed me 200 florins, and had brought 15 florins and a chandelier towards reducing the debt, which I advised her to send to you. I asked her to stay to dinner, which she refused. However, we hanselled your cup, as you know she is of a thirsty temperament."

In the same year in which his mother was arrested, the States of Styria ordered all the copies of the Kalendar for 1624 to be publicly burnt. There does not seem to be any reason for supposing that this insult proceeded from his old enemies the Catholics. They would, no doubt, take an active share in carrying it into effect; but it would appear that his former patrons were affronted at Kepler's giving the precedence in his title page to the States of Upper Ens, where he then resided, above the States of Styria.

In 1622, the Emperor Ferdinand, notwithstanding his own pecuniary difficulties, ordered the whole of Kepler's arrears to be paid, even those which had been due by Rudolph and Mathias; and so great was his anxiety to have the Rudolphine Tables published, that he supplied the means for their immediate completion. New difficulties, however, sprung up to retard still longer the appearance of this most important work. The wars of the reformation, which were then agitating the whole of Germany, interfered with every peaceful pursuit. The library of Kepler was sealed up by order of the Jesuits, and it was only his position as imperial mathematician that saved him from personal inconvenience. A popular insurrection followed in the train of these disasters. The peasantry blockaded Linz, the place of Kepler's residence, and it was not till the year 1627, as the title page bears, or 1628, as Kepler elsewhere states, that these celebrated Tables were given to the world.

The Rudolphine Tables were published at Ulm in one volume folio. These Tables were calculated by Kepler from the Observations of Tycho, and are founded on his own great discovery of the ellipticity of the planetary orbits. The _first_ and _third_ parts of the work contain logarithmic and other auxiliary tables, for the purpose of facilitating astronomical calculations. The _second_ part contains tables of the sun, moon, and planets; and the _fourth_ a catalogue of 1000 stars, as determined by Tycho. A nautical map is prefixed to some copies of the tables, and the description of it contains the first notice of the method of determining the longitude by means of occultations.

A short time after the publication of these tables, the Grand Duke of Tuscany, instigated no doubt by Galileo, sent Kepler a gold chain in testimony of his approbation of the great service which he had rendered to astronomy.

About this time Albert Wallenstein, Duke of Friedland, a great patron of astrology, and one of the most distinguished men of the age, made the most munificent offers to Kepler, and invited him to take up his residence at Sagan in Silesia. The religious dissensions which agitated Linz, the love of tranquillity which Kepler had so little enjoyed, and the publication of his great work, induced him to accept of this offer. He accordingly removed his family from Linz to Ratisbon in 1629, and he himself set out for Prague, with the double object of presenting the Rudolphine Tables to the Emperor, and of soliciting his permission to go into the service of the Duke of Friedland. The Emperor did not hesitate to grant this request; and would have gladly transferred Kepler's arrears as well as himself to the charge of a foreign prince. Kepler accordingly set out with his wife and family for Sagan, where he arrived in 1629. The Duke Albert treated him with liberality and distinction. He supplied him with an assistant for his calculations, and also with a printing press; and, by his influence with the Duke of Mecklenburg, he obtained for him a professorship in the University of Rostoch.

In this remote situation, Kepler found it extremely difficult to obtain payment of the imperial pension which he still retained. The arrears had accumulated to 8000 crowns, and he resolved to go to the Imperial Assembly at Ratisbon to make a final effort to obtain them. His attempts, however, were fruitless. The vexation which this occasioned, and the great fatigue which he had undergone, threw him into a violent fever, which is said to have been one of cold, and to have been accompanied with an imposthume in his brain, occasioned by too much study. This disease baffled the skill of his physicians, and carried him off on the 5th November, O.S. 1630, in the sixtieth year of his age.

The remains of this great man were interred in St Peter's Churchyard at Ratisbon, and the following inscription, embodying an epitaph which he had written for himself, was engraven on his tombstone.

IN HOC QUIESCIT VIR NOBILISSIMUS, DOCTISSIMUS ET CELEBERRIMUS DOM. JOHANNES KEPLERUS, TRIUM IMPERATORUM RUDOLPHI II., MATHIAE, ET FERDINANDI II., PER ANNOS XXX, ANTEA VERO PROCERUM STYRIAE AB ANNO 1594 USQUE 1600, POSTEA QUOQUE ASTRIACORUM ORDINUM AB ANNO 1612 USQUE AD ANNUM 1628, MATHEMATICUS TOTI ORBI CHRISTIANI, PER MONUMENTA PUBLICA COGNITUS, AB OMNIBUS DOCTIS, INTER PRINCIPES ASTRONOMIAE NUMERATUS, QUI PROPRIA MANU ASSIGNATUM POST SE RELIQUIT TALE EPITAPHIUM.

Mensus eram coelos, nunc terrae metior umbras: Mens coelestis erat, corporis umbra jacet.

IN CHRISTO PIE OBIIT ANNO SALUTIS 1630, DIE 5 NOVEMBRIS, AETATIS SUAE SEXAGESIMO.

This monument was not long preserved. It was destroyed during the wars which desolated Germany; and no attempt was made till 1786 to mark with honour the spot which contained such venerable remains. This attempt, however, failed, and it was not till 1803 that this great duty was paid to the memory of Kepler, by the Prince Bishop of Constance, who erected a handsome monumental temple near the place of his interment, and in the Botanical Garden of the city. The temple is surmounted by a sphere, and in the centre is a bust of Kepler in Carrara marble.

Kepler left behind him a wife and seven children--two by his first wife, Susanna and Louis; and three sons and two daughters by his second wife, viz.--Sebald, Cordelia, Friedman, Hildebert, and Anna Maria. The eldest of these, Susanna, was married a few months before her father's death to Jacob Bartschius, his pupil, who was educated as a physician; and his son Louis died in 1663, while practising medicine at Konigsberg. The children by his second wife are said to have died young. They were left in very narrow circumstances; and though 24,000 florins were due to Kepler by the Emperor, yet only a part of this sum was received by Susanna, in consequence of her refusing to give up Tycho's Observations till the debt was paid. Kepler composed a little work entitled "The Dream of John Kepler, or Lunar Astronomy," the object of which was to describe the phenomena seen from the moon; but he died while he and Bartschius were engaged in its publication, and Bartschius having resumed the task, died also before its completion. Louis Kepler dreaded to meddle with a work which had proved so fatal to his father and his brother-in-law, but this superstitious feeling was overcome, and the work was published at Frankfort in 1636.