by Max Caspar

View All Available Formats & Editions

A towering figure in intellectual history and one of the fathers of modern astronomy, the great mathematician Johannes Kepler (1571–1630) is best known for his discovery of the three laws of planetary motion, which paved the way for a dynamic explanation of the heavenly phenomena. At a time when the Ptolemaic view still prevailed in official circles, Kepler

See more details below


A towering figure in intellectual history and one of the fathers of modern astronomy, the great mathematician Johannes Kepler (1571–1630) is best known for his discovery of the three laws of planetary motion, which paved the way for a dynamic explanation of the heavenly phenomena. At a time when the Ptolemaic view still prevailed in official circles, Kepler undertook to prove the truth of the Copernican world view and through exceptional perseverance and force of intellect achieved that goal.
His epochal intellectual feats are completely and thoroughly described in this splendid work, considered the definitive biography of Kepler. Drawing on a wealth of primary sources, the author presents a fascinating and erudite picture of Kepler's scientific accomplishments, his public life (work with Tycho Brahe, the Danish astronomer; mathematical appointments at Graz, Prague, and Linz; pioneering work with calculus and optics, and more) and his personal life: childhood and youth, financial situation, his mother's trial as a witch, his own lifelong fear of religious persecution, his difficulties in choosing one of eleven possible young women as his second wife, and more, through his last years in Ulm and death in Regensburg.
Until his death in 1956, Professor Max Caspar was the world's foremost Kepler scholar. He had spent over two-thirds of his life assembling, cataloging, describing, analyzing, and editing Kepler's works. To this biography he brought tremendous learning and passionate enthusiasm for his subject, creating an unsurpassed resource on the life and work of one of history's greatest scientific minds. Originally published in German and superbly translated into English by C. Doris Hellman, Kepler will fascinate scholars and general readers alike.

Read More

Editorial Reviews

This fine biography of Johannes Kepler, the physicist best known for his discovery of the three laws of planetary motion, was first published in Germany in 1948. Later translated to English in 1959, this newly enlarged English edition is considered by many scholars to be the definitive account of Kepler's productive life. Annotation c. Book News, Inc., Portland, OR (

Product Details

Dover Publications
Publication date:
Dover Books on Astronomy
Sold by:
Barnes & Noble
Sales rank:
File size:
1 MB

Read an Excerpt


By MAX CASPAR, C. Doris Hellman

Dover Publications, Inc.

Copyright © 1993 Owen Gingerich
All rights reserved.
ISBN: 978-0-486-15175-5




1. Birth and ancestry

These were the times into which was born the first child of Heinrich Kepler and his wife Katharina, née Guldenmann. His birth took place in the little Swabian imperial city of Weil, today called Weil der Stadt, on Thursday, December 27, 1571, at two-thirty in the afternoon. The infant was baptized Johannes after the saint of the day, the Apostle John.

The Kepler family, from which the child was descended, had been located in Weil der Stadt for about fifty years. About 1520 the great-grandfather of Johannes, named Sebald, emigrated from his native city, Nuremberg, and settled in Weil der Stadt. He belonged to the craftsman's class and was a furrier by trade. The family which he founded in his new dwelling place was very numerous. His sons soon gained respect by their ability. Several were council members and the second of them, named Sebald like his father, became mayor and administrator of trusts in the city. His marriage to Katharina Mütter from neighboring Marbach was richly blessed with children. The fourth child, Heinrich, was the father of our Johannes. Like his wife he was twenty-four years old at the birth of their first child. Johannes' mother was the daughter of Melchior Guldenmann, the innkeeper and village mayor in nearby Eltingen. The family tree can be traced still further back. The father of that Sebald Kepler who moved to Weil der Stadt was the master bookbinder in Nuremberg, Sebald Kepner. Thus, not "Kepler," is his name spelled in Johannes Kepler's hand, in a document of a later date on which the above genealogical particulars rest. This was an arbitrary oral modification of the old family name Kepler, perhaps in assimilation of the name Kepner, frequently seen in the fifteenth century in Nuremberg.

While the immediate ancestors were craftsmen, if we go still further back in the family history, we get a different picture. Sebald Kepner or Kepler, the Nuremberg master bookbinder, was of noble descent, but driven by need he put aside the nobility and entered the craftsman's class in Nuremberg; perhaps the change of the name Kepner to Kepler is connected with this change in social position. According to a tradition worthy of belief, this Sebald was a son of Kaspar von Kepler, who toward the end of the fifteenth century appeared in Worms as court post-equerry. And this Kaspar von Kepler was in turn a son of Friedrich Kepler, the warrior who was knighted by Emperor Sigismund on the Tiber bridge in Rome at Whitsuntide, May 31, 1433. Not only did Johannes Kepler explicitly certify the report of this rise in rank later when, without boasting, he cited it in opposition to a Venetian nobleman, but it is much more amply corroborated by the patent of nobility of the year 1433, still extant in the Vienna peerage archives, according to which the brothers Konrad and Friedrich Kepler, because of their military services in the army of the emperor, had been distinguished in the way described. In this patent of nobility the coat of arms of the Kepler house also experienced a corresponding embellishment. The shield of the coat of arms is divided into a yellow upper and a blue lower field. In the upper field can be found the half figure of a red-robed angel with golden wings, who places his hand on the division line. On the helmet with red-yellow cover stands a blue-bordered yellow peaked cap, which is adorned on top by a yellow-blue-red padded roll, and from which issues a black heron's feather tuft on which is scattered golden tinsel. Upon request, this coat of arms was confirmed to the grandfather Sebald and his brothers in the year 1564 by the emperor. Johannes Kepler was in the habit of sealing with this coat of arms. It cannot be stated where that knightly ancestor, Friedrich, had his home and property. From the remark of our Kepler that Friedrich was knighted "with other Swabian knights" by Emperor Sigismund, it might be concluded that the home was in Swabia. Yet such a far-reaching conclusion should scarcely be drawn from this remark. From theexplanation in the letter of nobility, that the emperor wished to treat with special distinction those men "whose forefathers had always shown themselves useful to the Holy Empire," it follows that their distant ancestors were confirmed as valiant bondsmen, as, indeed, old documents report various heroic deeds by bearers of the name "Keppler" or "Kappler" without its being established that these men belonged to our Kepler family. Nor is it certain that Friedrich Keppler, the thirteenth century noble who originated from Salzburg, was a member of the family. A document in the Vienna archives of nobility reports that Friedrich had proved himself in wartime and peacetime by his bravery and faithfulness; it is noteworthy that this nobleman likewise carried an angel on a shield as a family coat of arms. That soldier's blood flowed in the veins of Kepler is also confirmed by the tale that both the great-grandfather, Sebald, and subsequently the grandfather, Sebald, were supposed to have received privileges for military laurels earned under the banner of Charles V and his successors. We do not know what moved the great-grandfather, Sebald, to transfer to little Weil, leaving Nuremberg, where applied art and industry had created a brilliant tradition and promised a capable man rich opportunities. Did he visit Weil der Stadt on his travels and get stuck, or had he perhaps been induced by relatives in that town to settle there? At any rate, it is noteworthy that evidently toward the end of the fifteenth century bearers of the name Kepler were already living in Weil as can be proved by the registers of the University of Tübingen. Further information about this, as well as some other details worth knowing concerning the Kepler family history, so far as they deal with Weil der Stadt, cannot be established since the relevant archives are no longer extant. They "Vanished in dark smoke" at the end of the Thirty Years' War when the French, in October, 1648, just at the time when the Westphalian peace was signed, besieged the city, setting it afire. A large proportion of the buildings was reduced to ruins and ashes and both the parish registers and most of the archives went up in flames.

2. Weil der Stadt

Small and crowded together though Weil der Stadt was, its inhabitants, nevertheless, were always inspired with self-esteem and pride in their independence, as privileged citizens of a free imperial city. Founded by the Hohenstaufens, this little city received imperial freedom toward the end of the thirteenth century after the interregnum under Rudolph I. An idea of the city's earlier appearance in Kepler's time can well be formed from the picture that the city presents today. The little streets, the spacious market place, which is surrounded by high gabled houses, the towers and gates of the city wall, which is still preserved to a considerable extent, are seen, as formerly, grouped in friendly fashion. In a rolling landscape on the edge of the Black Forest, surrounded by gardens and meadows, fields and woods, the place was built up against a gentle slope which falls away toward the broad valley of the little river Würm. The crown of the picture and its loveliest jewel is the three-steepled Gothic church, situated on high and visible from afar, towering above the tangle of roof-tops like a magnificent minster. It gathers the houses around it and takes them under its care, as a brood-hen does her chicks, an eloquent witness to the pious soul of the ancestors, who well knew what to make the focal point of their existence. With Swabian diligence, the inhabitants attempted to keep their city in neat order and, in a democratic spirit, tried to protect its rights. Mostly peasants and craftsmen, among whom the leather dressers and weavers stood out, they had to direct their cares and hopes to the exigencies of life. They let the path of the sun, the moon and the stars go just as it went, and advanced science lay beyond their intellectual horizon, although some clever heads went forth from the city. Since the community in that earlier time consisted of only about two hundred burghers and their families, the free imperial city of Weil had no weighty voice in the state proceedings in the Holy Roman Empire. When once in a century an emperor came to visit, it was an event that was carefully recorded in the annals. What otherwise aroused men's minds were squabbles over tolls and hunting rights with the neighboring duke of Württemberg, whose land surrounded the urban district. Military events, to be sure, also repeatedly aroused the townspeople from their quiet. That they fought well when they fought for their freedom is proved by the part which they took on the side of the confederation of towns in the unhappy battle in neighboring Döffingen in the year 1388. In this battle against the duke of Württemberg sixty of their citizens were killed.

In Weil der Stadt the Reformation led to long continued tensions and disputes. Although the evangelical doctrine found followers among the citizens very soon after Luther's appearance, it did not succeed in winning over the majority. The parish church always remained in the hands of the Catholics. At the time of Kepler's birth, there was still no Protestant preacher in the city. A few years later, the followers of the new creed, with the support of the Württemberg duke, struggled in vain with the city councilor for the toleration of the evangelical faith, for the granting of a special church or chapel and for the employment of a clergyman of their own. The councilor considered it a special concession when he allowed the Protestant townsmen to receive sermon and sacrament abroad and permitted a preacher of their creed to come and administer communion when they were in danger of death. It was, indeed, a victory for the Protestants that a few years thereafter evangelical baptism was permitted in the city. The Kepler family, especially Johannes' grandfather, Sebald, were among the most prominent and most active advocates of the Lutheran teaching. That the latter, as leader of his coreligionists, retained the office of mayor, in spite of the Catholic majority, speaks for his ability and the high regard that he was able to earn among his fellow citizens. In the same period, members of the Fickler family were prominent among the promoters of the Catholic interests. This was particularly true of Johann Baptist Fickler, prothonotary of the archbishopric of Salzburg, who was active in the Counter Reformation as an influential opponent of Protestantism. Despite the difference in faith, the Kepler and Fickler families were related by marriage. For this reason, many years later, Kepler's son Ludwig succeeded to the scholarship that a relative of the Fickler family had founded in Tübingen. The circumstances described above explain why no one knows where Kepler was christened, whether in the parish church by a Catholic clergyman, or, what is more probable, by a Protestant preacher in one of the neighboring villages, most likely Magstadt.

Grandfather Sebald's house was situated, tradition has it, near a corner of the market place, in a short alley leading to the church, so that a glimpse of the market fountain with the statue of Emperor Charles V and the mighty west tower of the house of God was afforded. This family house fell a victim to the city fire of 1648. There is reason, however, to believe that it was rebuilt in its earlier form. It is correctly considered the birthplace of our Johannes, since his father, Heinrich, continued to live in it after his marriage on May 15, 1571. Although it appears small from the outside, inside it is sufficiently roomy to hold a large family. The mayor, Sebald, apparently attained greater wealth only in later years, mainly by inheritance.

3. Kepler's family

When he was about twenty-five years old, Johannes Kepler made notes about the characteristics of his grandparents and parents, as well as about some accidents and misfortunes, such as life brings, so that we gain a picture of their character and the life in the house in which he passed his first years. He did this in an appendix to the birth-horoscope of these ancestors, because at that time he was much occupied with astrology and believed that personality was influenced by the position of the planets at the time of birth. He described his Grandfather Sebald as proud and arrogant in manner, hot-tempered, impetuous, stubborn and sensual; his face was red and rather fleshy; his beard lent him an air of importance. He was able, without being especially eloquent, to give good and wise instructions and to enforce their observance. Kepler's grandmother was, according to his description, very restless, clever, inclined to die, but zealous in religious matters, slender, of fiery nature, lively, ever on the move, jealous, spiteful, resentful. Kepler says that Saturn in trigon to Mars in the seventh house, had made his father, Heinrich, an immoral, rough and quarrelsome soldier. The mother, too, does not come off so well; she was small, thin, dark-complexioned, garrulous, quarrelsome and generally unpleasant. This is no brilliant ancestral gallery which Kepler parades before us, and his character portraits are all the more surprising as it is known that reverence for his relatives was a prominent trait in his nature. It must be remembered here that he made these notes only for himself to demonstrate the agreement of the characters with the heavenly constellations. In this way it could easily happen that he searched the heavens mainly for an explanation of the bad qualities as a kind of apology and thus let the good ones recede into the background.


Excerpted from KEPLER by MAX CASPAR, C. Doris Hellman. Copyright © 1993 Owen Gingerich. Excerpted by permission of Dover Publications, Inc..
All rights reserved. No part of this excerpt may be reproduced or reprinted without permission in writing from the publisher.
Excerpts are provided by Dial-A-Book Inc. solely for the personal use of visitors to this web site.

Read More

Customer Reviews

Average Review:

Write a Review

and post it to your social network


Most Helpful Customer Reviews

See all customer reviews >