Preface by Tycho Brahe to the noblest emperor Rudolph the 2nd


Astronomy is a very ancient science, divinely entrusted to mankind from the time of Adam Protoplastus. It is by far the most prestigious, insofar as what is celestial and sublime certainly surpasses what is terrestrial and inferior. This divine astronomy, I say, drawing its origin from the very senses of our eyes, observing the wandering movements of the stars to the outer reaches of the world, has vexed both the geniuses and the abilities of the most eminent men for the long span of time since the beginning of things. The majesty of the highest and thrice-greatest God is surely so great that the wisdom of his works can not be exhausted by any of his creatures. But since the gaze of the eye alone was unable to capture all the mysteries of the celestial theater - which are wonderful beyond measure - and all the intricate-appearing differences, for which subtlety and accuracy was needed, various craftsmen in every age have contrived means and instruments by which their vision might be aided in perceiving the obscure motions of the stars. Hence, there are those columns, which Joseph, the writer about Jewish matters, reports the descendants of Adam had built in Syria and had their discoveries inscribed on them, so that those who came after them would remember.1 The very great and extravagant pyramids of the Egyptians and other peoples also pertain to this. And many other devices that were constructed for this purpose by the most ancient kings were once observed, such as in India, Syria, Arabia, Chaldea, Ethiopia, Egypt - especially one in the Colonnade of Alexandria2 - and also elsewhere in the surrounding regions, where men diligently applied themselves to the study of the stars. For, in astronomy it is first of all necessary to obtain very many observations, taken over a long period of time by means of instruments that are not liable to error. And then, through geometry, using convenient hypotheses that have been contrived, these observations are arranged into continuous quantities and a motion that is both circular and uniform (which celestial bodies natural strive for and execute without ceasing). But through arithmetic, they are arranged into discrete quantities, so that the circuits of the celestial bodies are determined for particular times and places.3 But from all those who have strenuously worked in this field, only those observations that were recorded by Timocharis,4 Hipparchus,5 Ptolemy,6 Albategnius,7 King Alphonso,8 and in the previous generation, Copernicus,9 have come down to us, although the traditions of the two former, at least, depend on Ptolemy's account. One can understand which instruments these men chiefly used for measuring the stellar phenomena from what they have written. Among them I find these three to be excellent: the parallactic rulers,10 the zodiacal armillaries,11 and the torquetum, which the arabs preferred to use (as also the plane astrolabe). The rest are of lesser importance. However, perhaps there were many others that were not mentioned in the literature and have not at all come down to us, which easily could have perished in the such great confusion and so frequent changes of the world, in which so many wars and devastations have occured repeatedly (which should be lamented). More recent astronomers added the quadrant, the radius, and the astronomical ring, and then also some of still less value. However, the fact that the motions of the stars, which are accurately considered in our time, do not at all so reveal themselves as the calculation derived from the observations of other experts, whether ancient or recent, predicts, causes us to suspect, non unjustly, that the means and instruments that they used in the course of observing were by no means free from defects of every kind. Even if the rest of the data were ignored, the locations of the fixed stars themselves, which are placed differently than the Hipparchian designation indicates, as recounted by Ptolemy and from him propagated to us, demonstrates this sufficiently. This must have been the case even for the ancients, when emperors and kings readily provided funds for constructing such instruments, whereby they would be magnificently made from a solid and metallic material and rightly have suitable size. Even more so for those that Copernicus made at his own expense in the previous generation, being sufficient neither in the solidness of the material nor even the size proper to those uses to which they were appointed, as is partly evident from his book De revolutionibus,12 and partly from those instruments considered to have been used by him that which still remain. One of these, clearly a parallacticum, entirely made of wood, not quite suitable for observations, is in my possession. On this account, thinking carefully, ever since my youth, whether it would not be possible for this insufficiency to be relieved, I then went to the trouble of successively constructing astronomical instruments with great care and at unbelievable expense. With these it was possible to examine the stellar phenomena more accurately than was done by our predecessors (without meaning any disrespect).13 But although those that I made in my youth, when neither my knowledge nor my judgement were sufficiently mature, did not quite accurately attain the desired goal, nevertheless, as I became older and my experience fuller, I at length acquired other, larger and more excellent instruments and I saw to it that they were skillfully elaborated, of such a kind as perhaps hardly any earlier age has seen - ones that exhibit the highest accuracy and dependability, as it was intended they should. Moreover, I constructed various and multiple instruments, for obvious reasons: First, because I would prove an observation to be free of all error, by investigating the same one by different means, and then, too, so that if some of them would produce any hidden defect (also because Ptolemy is seen to complain loudly about the same kind of instruments, which were made of solid metal and once used to stand in the Colonnade at Alexandria), others would then be at hand, which would correct it and demonstrate their exact dependability, and in addition, so that the observers' sharp-sightedness in sighting the instruments and their diligence in reckoning - there should be at least six or eight of them - to be compared in turn, might be examined, with no one of them having knowledge of what another has determined. To say nothing about the fact that the variety itself makes the observers more diligent and more eager, and is in itself delightful. It also happens that among those things that come to be explored, some comply with certain devices better than with others in order to be investigated properly, with the result that some require certain known altitudes only, and certain azimuths together with these, while several demand only distances, requiring certain declinations, certain equatorial distances. Some instruments are suitable for obtaining longitudes and latitudes at the same time, and others right ascensions and declinations, and so on with the rest of them, since being administrated by various means, they better serve celestial observation. Therefore, even for this cause alone a large number and variety of instruments is certainly necessary. Seeing that those things that are invented and built by men in the exercise of the arts should be communicated, for a liberal society of human beings and for the propagation of the arts to posterity, I considered that so sublime and useful devices should not be reserved for me alone, but shared with others, if (as I hope) there are those to be found in other places, who are touched by so difficult a concern. And to that end, I am submitting to the press those devices which I have had in use hitherto, delineated and represented by their images, insofar as it was possible that these be executed so quickly. I wished to present them to the public accompanied by a concise explanation of each of them, as will be evident in the following pages. Moreover, in arranging them, I have observed this method chiefly: first I described those devices that investigate the altitudes and azimuths of the heavenly bodies, some of which reveal only altitudes, but some both altitudes and azimuths. Here the smaller and less important instruments come first, and the rest, those that are greater and grant more exact precision, follow. That takes care of the first eight, although later, too, I display and mention a certain very large quadrant, intended for altitudes only, which I once used at Augsburg, in my youth. Why, for what reason it was made, will be mentioned later. Then follow the equatorial armillary instruments.14 The first among these, the zodiacal armillary, exhibits the longitudes and latitudes of the heavenly bodies with greater facility and dependability than perhaps was done by the ancients. And since it does not hit the nail on the head (as they say), for certain reasons set forth there, three others follow, equatorial armillaries, the first of which consists of three circles and an axis. The second requires four with this. But the third, and the greatest, accomplishes the whole matter with one and a half circles and an axis, stretched around, as in the rest, and shows declinations as well as right ascensions, together with the distances from the meridian, as precisely as possible. In the third group, I have arranged those instruments that serve for examining the angular distances between the stars and one for obtaining rather large distances as well as smaller ones, so long as they do not exceed a sixth part of a circle. There are among these four in number that are devoted to measuring distances, although I also possess more, which it was not possible to manage to draw and have cut into wood quickly enough. Among the ones displayed here, there is one that takes down the angular distances of the heavenly bodies even much greater than a sixth part of a circle, up to a half circle itself. Finally, a certain instrument that I used on the new star of the year 1572, a star to be greatly wondered at, seeing as it was located with the altitudes that were to be taken down in an especially declined place, has been added after the previous group, as has that enormous quadrant, which I mentioned previously, and which I had built for me many years ago near Augsburg, in the garden of councilman Paul Haintzel, whom I remember fondly. He was very eager about these pursuits while he lived. Since it no longer exists there - it lasted only for five years - I did not wish to give it a place among the rest of the instruments that measure altitudes, but rather I placed it at the end. And after this, there is a certain steel quadrant, which I brought up earlier, yet is placed here otherwise. When that was done, I at last added a short description of other of my instruments, which are not yet drawn and which I am not ready to exhibit, where also is added some indication of those that I am still thinking of constructing to great advantage. I will communicate a fuller explanation of each of these - those that are ready to use as well as others that are to be elaborated - in due time, when the occasion warrants. But now, striving for brevity, I found it agreeable to touch on those instruments that pertained to this matter with at least a few words, even though their images were not yet prepared. Finally, as a finishing touch, I explain that very great globe, made of brass, which comprehends 1000 fixed stars that were placed by me with the greatest care and precision many years ago now, insofar as something so difficult and serving multiple uses can be elucidated in a few words. Then I come to the end of the description of the instruments. To all this I have attached some mention of those things that have been thus far accomplished by me and those that remain to be completed in the future; and then I have added a few particular letters of eminent men commending the task at which I have labored. Indeed, in place of a kind of appendix, it seemed reasonable to add in addition the architectural work, portrayed and displayed, which reveals to the eyes the structures that were designed by me and produced for this use in the several years preceeding, granted that to certain people it could seem to be not wholly necessary at this place, since indeed those who will have wanted to apply serious attention to them and are equal to administering the funds will easily devise by themselves plans for the buildings brought together here, especially when the appropriateness of the place has been grasped. However, so that I might show in advance some kind of idea in accordance with those things that have been elaborated by me in the area immediately around them, I decided that it would be not wholly beside the point if I would attach these astronomical buildings, displayed together. And indeed, these are just the things for which this book was completed, as will become evident to one who is viewing them. But if other things have been mixed in and added, the prudent reader will discern them by himself without difficulty, so there is no need for me to advise him. But to you, august Emperor Rudolph II, gracious lord, I offer, relate, and dedicate this and my other astronomical labors, humbly and with an effort devoted to the public good. For, just as your imperial majesty, as the highest preeminence, far surpasses other, lesser men, so too your imperial majesty is not unaware that it is your honor and duty to emulate in immensity the heaven and the celestial, which far surpasses the terrestrial and the common. And for this reason these sublime studies should be valued and cultivated. That ancient poet Manilius seems to have reflected on this when, writing about this celestial art to Augustus, the second monarch of the Roman Empire,15 he distinguished it with this elegy, not undeservedly:
[Moreover, nature proffered her aid
and of her own accord opened up herself,]
deigning first to inspire those kings
whose minds reached out to heights bordering on heaven.16
Therefore, most august caesar, kindly receive those tasks that I have borne for many years now, almost from my childhood, with untiring labor and at unbelievable expense, by which that divine and greatly royal science of astronomy, which possesses a chief place, before all others, might finally be restored to wholeness and handed down to posterity more correct than at any time before. I believe that both me and this work itself, which I treat with remarkable enthusiasm in the following text, will be as agreeable to you as possible. The more that the honor and majesty of the best and greatest God, which shines in celestial things more than in other aspects of this great world theater, comes to be known more correctly, the more it is increased and esteemed among the inhabitants of the earth; Moreover, since to preserve, protect, and promote for all posterity these so excellent things, which are almost extraordinary in human affairs, will not diminish Your Imperial Majesty's fame and reputation, may it shine brighter for that and endure as long as the sun and heavenly bodies last, because from these alone, which are perpetual and constant - of a celestial kind - one may acquire an eternal name and undiminished honor. As for the rest, the sublunary and terrestrial, just as they are liable to multiple changes, so also whatever glory is obtained from them is fleeting, fickle, and inconstant, and does not emulate eternity, as do those celestial things about which I am speaking. May that highest and inscrutible author of these things consider it worth while to bestow on Your Imperial Highness a good mind, bodily health, peace, and an abundance of the good things of this world, with a calm and happy empire, chiefly for his glory and the illumination of things created by him and for the benefit of your subjects, for which I wish and pray humbly and from my heart. May Your Imperial Highness be well and kindly receive this little omen of this new year, which I offer with what reverence I can as a token of my courageous and humble spirit. Communicated from the Ranzov Castle, Wandesburg, which is near Hamburg, on the border of Germany and the Cimbrian Penninsula, on the day before the first day of January of the year 1598 of the common Christian era.

1 Iosephus Flavius, Jewish historian from the 1st century A.D. He took part in the Jewish insurrection at the time of the emperor Nero but he went over to the Roman side and was called Flavius owing to the support of the Flavius family. His Greek, originally Aramaic book The Jewish War, describing the reasons for and events of the war in 66 to 73 A.D., is based on his experience. Jewish Antiquities describes the history of the Judeans up the period of Nero. His Autobiography and Contra Apion are his other treatises dealing with the relations of Judeans and Romans. - In Jewish Antiquities (I,68-71) he wrote: (Descendants of Seth, the son of Abel)... "also discovered the science of the heavenly bodies and their orderly array. Moreover, to prevent their discoveries from being lost to mankind and perishing before they became known - Adam having predicted a destruction of the universe, at one time by a violent fire and at another by a mighty deluge of water - they erected two pillars, one of brick and the other of stone, and inscribed these discoveries on both; so that, if the pillar of brick disappeared in the deluge, that of stone would remain to teach men what was graven thereon and to inform them that they had also erected one of brick. It exists to this day in the land of Seiris." (translated by H. St. J. Thackeray, Josephus in nine volumes, IV, Cambridge, Mass.: Harvard Univ. Press; London: W. Heinemann, 1978). Cf. Opera omnia I, 148, where Tycho paraphrased this passage and pointed out that one of the columns was still in Syria (instead of in Seiris, which is nowadays unidentified) in the time of Flavius. On this basis he argued for the antiquity of astronomy: "And in this way the knowledge of the stars got from the sons of Adam to their descendants."
2 By the term porticus Tycho meant here the Museion in Alexandria, i.e. the temple of the Muses. This was a famous school with a rich library, built by the Ptolemaic dynasty at the end of the third century B.C., where scientific life was concentrated for several centuries.
3 Here Tycho uses mathematical terms that are in common use today: (continuae and discretae quantitates).
4 Lived around 290 B.C. Together with Aristyllus he made up the first catalogue of stars.
5 Greek astronomer (2nd century B.C.) working mostly in Rhodes. He made extensive observations of stars and planets, produced a new catalogue of stars, discovered precession (by comparison with observations made by Aristyllus and Timocharis), and improved the theory of Solar and Lunar motion by introducing the eccentrics and epicycles. He was also an outstanding mathematician -- he developed trigonometry for both planar and spherical triangles and he composed the first goniometric tables (of lengths of chords).
6 Claudius Ptolemy (100 ? - 178), Alexandrian astronomer, mathematician and geographer. His treatise Megale syntaxis (Great system) was translated into Arabic with the title Almagest, which it retained in the Latin translation. It was the basis of astronomy until Tycho's time. Ptolemy summarized the knowledge of his predecessors, especially Hipparchus (see footnote 5). His main original contribution was the improvement of Lunar and planetary theories (within the framework of geocentrical model). In the treatise Geographike hyphegesis (Instructions on Geography, abbreviated Geography) he explains the basis of geography and cartography and he gives geographical coordinates of 8000 localities, measuring longitudes from the Canary Islands. Among his other treatises, let us mention at least Planisphaerium, with mathematical elements of stereographic projection, Analemma, with elements of gnomonics, Tetrabiblos, explaining astrology, Tabulae manuales, and Optics.
7 Al-Battani (850 ? - 929) wrote in al-Raqqa, along the Eufrates River, a series of astronomical tables that were translated into Latin as De scientia stellarum in the middle of 12th century by Robert of Chester and later by Plato of Tivoli (Nuremberg, 1537). Cf. Olaf Pedersen, Early physics and astronomy, Cambridge: Cambridge University Press, 1993.
8 Alphonso X, the Wise (1221 - 1284), king of Castille and Leon was well known as a lawgiver and writer. He achieved recognition as a supporter of the natural sciences, including astronomy. Around 1272 he stimulated the completion of so called Alphonsine Tables, one of the most widely used astronomical tables in the Middle Ages. The tables were based on Toledean tables from the eleventh century and they were refered to the year 1252 of Alphonso's coronation. They were written originally in the Castilian language, but they soon spread over the whole of Europe in Latin translation (see e.g. E. Poulle, Les Tables Alphonsines avec les Canons de Jean de Saxe, Paris 1984; they are also included in the astronomical manuscript of the Czech King Wenceslas IV from 1392 - 1393, held in Vienna, Nationalbibliothek, cod. lat. 2352.). It was first printed in 1483 and other editions soon followed. In 1276 - 1277 Alphonso commissioned a group of Jewish, Arabic and Christian scientists (e.g. Rabbi Zag) to complete the astronomical encyclopedia Libros del saber de astronomia (Book of knowledge of astronomy, ed. Manuel Rico y Sinobas, Madrid 1863 - 1867), partly based on translations of Arabic texts, and partly original, with prefaces written by Alphonso himself. - On the content of both treatises, see Owen Gingerich, "Astronomical Scrapbook," Sky and Telescope 1985, 206-208.
9 Nicolaus Copernicus (1473 - 1543), Polish astronomer and author of the modern heliocentric system. He was a clergyman and spent most of his life in service to his diocese. The first treatise formulating his theory was the Commentariolus (Nicolai Copernici de hypothesibus motuum coelestium a se constitutis commentariolus), written about 1530. Detailed explanation and argumentation was given in his famous De revolutionibus orbium coelestium, published in Nuremberg in 1543. Tycho Brahe referred to Copernicus as the supreme astronomical authority and often compared their results.
10 That is, the triquetrum.
11 That is, the armillary sphere. Throughout the text, Tycho used the plural of the noun armilla to denote the armillary sphere, and we preserve this in our translation.
12 Nicolaus Copernicus, De revolutionibus orbium coelestium libri sex (On the revolutions of the celestial spheres), Nuremberg 1543.
13 The phrase absit invidia dicto (verbo) was often used by Titus Livius in his treatise Ab urbe condita e.g. IX, 19 etc.
14 In the Tycho's text there is by mistake armillae aequinoctiales.
15 Assuming that Tycho used the expression Augustus in the sense noble (as it is translated here), he really meant the second Roman Emperor, i.e. Tiberius (governed 14 - 37 AD). If he had in mind Augustus (governed 27 BC - 14 AD), he should have correctly written that he was the first Roman Emperor. Marcus Manilius lived and wrote during the epoch of both emperors but he devoted his work to Tiberius only. His work was first published by J.J. Scaliger (Paris 1579), hence the edition was accessible to Tycho.
16 Marcus Manilius, Astronomica I, 41-42. English translation by G. P. Goold, Harvard University Press, London 1977, pp. 7 - 9. The text in brackets was not presented by Tycho and is added here to provide the context.


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