Tycho v. Ursus: The Build-up to a Trial,Part 1

The following abbreviations are used throughout the present series of articles:

KGW = von Dyck W. Caspar M. , (eds), Johannes Kepler: Gesammelte Werke (22 vols to date; Munich, 1938–).

KOO = Frisch C. , (ed.), Joannis Kepleri astronomi opera omnia (8 vols, Frankfurt and Erlangen, 1858–71).

Jardine , Kepler's A defence of Tycho = Jardine N. , The birth of history and philosophy of science: Kepler's A defence of Tycho against Ursus with essays on its provenance and significance (Cambridge, 1984, rev. edn 1988).

Launert , Nicolaus Reimers = Launert D. , Nicolaus Reimers: Günstling Rantzaus—Brahes Feind. Leben und Werk (Munich, 1999).

Mosley , “Bearing the heavens” = Mosley A. , “Bearing the heavens: Astronomers, instruments and the communication of astronomy in early-modern Europe”, Ph.D. dissertation, Cambridge, 2000.

Rosen , Three Imperial Mathematicians = Rosen E. , Three Imperial Mathematicians: Kepler trapped between Tycho Brahe and Ursus (New York, 1986).

TBOO = Dreyer J. L. E. , (ed.), Tychonis Brahe Dani opera omnia (15 vols, Copenhagen, 1913–29).

KOO , i, 215–87 (to which all subsequent accounts are indebted); Dreyer J. L. E. , Tycho Brahe: A picture of scientific life and work in the sixteenth century (Edinburgh, 1890), 27, 183–4, 268–76, 288–302; Schofield C.J. , Tychonic and semi-Tychonic worldsystems (New York, 1981), 108–39; Jardine , Kepler's A defence of Tycho against Ursus, chaps. 1–5; Gingerich O. and Westman R. S. , The Wittich connection: Conflict and priority in late sixteenth-century cosmology (Philadelphia, PA, 1988), 50–69; Rosen , Three Imperial Mathematicans; Thoren V. , The Lord of Uraniborg: A biography of Tycho Brahe (Cambridge, 1990), 260–1, 390–9, 432–9, 453–61; Launert , Nicolaus Reimers, 72–108, 285–365; Mosley , “Bearing the heavens”.

On the significances of Contra Ursum, see, for example, Jardine N. , “The forging of modern realism: Clavius and Kepler against the sceptics”, Studies in history and philosophy of science, x (1979), 141–73; Eastwood B. , “Kepler as historian of science: Precursors of Copernican heliocentrism according to De revolutionibus, I, 10”, Proceedings of the American Philosophical Society, cvi (1982), 367–94; Barker P. and Goldstein B. R. , “Realism and instrumentalism in sixteenth-century astronomy: A reappraisal”, Perspectives on science, vi (1998), 232–58; Martens R. , Kepler's philosophy and the new astronomy (Princeton, 2000), chap. 3; Jardine N. , “The many significances of Kepler's Contra Ursum”, in Di Liscia D. (ed.), Festschrift für Volker Bialas, Algorismus (in press).

See especially Gingerich and Westman , The Wittich connection (ref. 1); Mosley , “Bearing the heavens”.

See KOO , i, 230–1. Translations of the two legal documents and of most of the relevant correspondence are provided in Rosen , Three Imperial Mathematicians.

For very much fuller accounts of the course of the controversy, see Rosen , Three Imperial Mathematicians; Gingerich and Westman , The Wittich connection (ref. 1); Granada M. A. , El debate cosmológico en 1588: Bruno, Brahe, Rothmann, Ursus, Röslin (Naples, 1996); Jardine N. and Segonds A. , La guerre des astronomes (Paris, forthcoming).

On Ursus's and Tycho's world systems, see Heninger S. K. Jr , The cosmographical glass: Renaissance diagrams of the universe (San Marino, CA, 1977), 53–56; Schofield , Tychonic and semi-Tychonic world systems (ref. 1); Gingerich and Westman , The Wittich connection (ref. 1); Granada M. A. , El debate cosmológico en 1588 (ref. 5).

Cf. Fundamentum astronomicum, 40v.7–8, where Ursus hopes shortly to provide “a genuine and in all its numbers most perfect and absolute astronomy”; and TBOO, iv, 157.35–37, where Tycho defers a comprehensive and precise account to a projected work.

Gingerich O. and Voelkel J. R. , “Tycho Brahe's Copernican campaign”, Journal for the history of astronomy, xxix (1998), 1–34; see also Goldstein B. and Barker R. , “The role of Rothmann in the dissolution of the celestial spheres”, The British journal for the history of science, xxviii (1995), 385–403.

Ursus , Fundamentum astronomicum, 37r: 6–9; De astronomicis hypothesibus, Aii,r: 32–35.

For details of Ursus's travels, sojourns and activities in this period, see Launert , Nicolaus Reimers, 23–67.

TBOO, vii, 125.20–40; 135.38–42.

TBOO, vii, 387.16–19.

TBOO, vii, 149.7–41.

TBOO, vii, 387.16–388.41.

TBOO , vi, 61.41–62.4. Hans Raeder and others following him have suggested that Tycho interpolated this insulting reference to Ursus into the published version of the letter: See Raeder H. , “Om Tycho Brahe's astronomiske brevvexling”, Edda, xiv (1920), 103–17; Rosen , Three Imperial Mathematicians, 225–6; Thoren , The Lord of Uraniborg (ref. 1), 393–4. That Tycho was innocent of this editorial impropriety is shown by Mosley A. Jardine N. and Tybjerg K. , “Epistolary culture, editorial practices, and the propriety of Tycho's Astronomical Letters”, Journal for the history of astronomy, xxxiv (2003), 421–51.

TBOO, vi, 156.38–158.26.

TBOO, vi, 179.19–180.11. On Tycho's confusion on this score, see Mosley , “Bearing the heavens”, 310–11.

The letter is cited by Ursus in De astronomicis hypothesibus, I3,v; it was later published by Tycho in his Mechanica with Ursus's name replaced by “N. N.” (TBOO, v, 121.34–41). This most probably stands for “Nomen Nescio”, as applied to a person or work whose name should not be mentioned. Another possibility is “Non Nominatus”, quite commonly applied in the period to anonymous works.

TBOO, vii, 321–326.37.

TBOO, vi, 3. On Tycho Brahe's privileges for this and other books, see Mosley , “Bearing the heavens”, 278–80.

Launert , Nicolaus Reimers, 343–51.

On Ursus's De astronomicis hypothesibus see Jardine , Kepler's A defence of Tycho, chap. 2; Launert , Nicolaus Reimers , 285–320; and the third and fourth of the articles in the present collection.

On Tycho's peregrinations following his fall from grace, see Thoren , The Lord of Uraniborg (ref. 1), chap. 11; Christianson J. R. , On Tycho's island: Tycho Brahe and his assistants, 1570–1601 (Cambridge, 2000), chap. 10.

TBOO, viii, 46.37–40; 50.36–51.6; 56.12–13.

TBOO, viii, 44–48; KGW, xiii, no. 92.

TBOO, viii, 56.28–30; 58.16–59.2.

KOO, i, 230; transl. in Rosen , Three Imperial Mathematicians, 246–50. On Hansen, see Christianson , On Tycho's island (ref. 23), 340–3.

KOO, i, 230–31; transl. in Rosen , Three Imperial Mathematicians, 250–3.

TBOO, viii, 180.40–181.7; 210.35–42.

TBOO, viii, 136.13–15.

TBOO, viii, 371.11–28.

TBOO, viii, 181.12–18.

TBOO, viii, 141–4; KGW, xiii, no. 112.

TBOO, viii, 203–11; KGW, xiv, no. 145.

On Kepler's activities in this period, see Caspar M. , Kepler, transl. and ed. by Hellman C. D. , with bibliographical citations by Gingerich O. and Segonds A. (New York, 1993), 96–121.

Jardine , Kepler's A defence of Tycho, 86.24–29; KGW, xx/1, 18.9–12.

KOO, i, 281–4; KGW, xx/1, 66–96; transl. in Jardine , Kepler's A defence of Tycho, 67–71.

TBOO, viii, 371.24–28.

See Langbein J. H. , Prosecuting crime in the Renaissance: England, Germany, France (Cambridge, MA, 1974), 198–202. We thank Julian Martin for advice on legal procedures in the period.

TBOO, viii, 343.35–36; KGW, xiv, no. 173. 139–40.

TBOO, viii, 281.18–282.17.

See also Launert , Nicolaus Reimers, 343–50.

On the possible reasons for Ursus's withdrawal from Prague, see Launert , Nicolaus Reimers, 99.

TBOO, viii, 343.34–35; KGW, xiv, no. 173. 138–9.

On the date and circumstances of Ursus's death see Launert Nicolaus Reimers , 102–8.

TBOO, viii, 343.40–41; KGW, xiv, no. 173. 143–4.

TBOO, viii, 344.2–7; TBOO, xiv, 209, no. 203.

TBOO, viii, 343.41–344.12.

TBOO , viii, 344.12–16; KGW, xiv, no. 173. 158–161.

KGW, xx/1, 70–82.

KGW, xx/1, 70–72.

See Kepler's account of his activities in this period in a letter of 1605 to Sørensen: KGW, xv, no. 323. 192–203.

See the account of Ursus's arrival in Prague given by the Imperial Physician, Háyek Thaddeus , in his letter to Tycho of 29 August 1591: TBOO, viii, 305.8–12.

On the world system presented in Fundamentum astronomicum, see Launert , Nicolaus Reimers, 155–207; Granada M. A. , Sfere solide e cielo fluido: Momenti del dibattito cosmologico nella seconda metà del Cinquecento (Naples, 2002), 263–78.

On the copying and manuscript circulation of Tycho's letters see Mosley A. , “Tycho Brahe's Epistolae astronomicae: A reappraisal”, in Papy J. van Houdt T. Tournoy G. and Matheeussen C. (eds), Self-presentation and social identification: The rhetoric and pragmatics of letter writing in early-modern times (Leuven, 2002), 449–68.

TBOO, vi, 61.41–62.35; 179.2–180.11.

Epistolae astronomicae was published “with the privileges of the Emperor and certain Kings [CUM CAESARIS ET REGUM QUORUNDAM PRIVILEGIIS]”: TBOO, vi, 3.

See Fabian B. , (ed.), Die Messkataloge des Sechzehnten Jahrhunderts: Faksimiledrucke. Band V. Die Messkataloge Georg Willers. Fastenmesse 1593 bis Herbstmesse 1600 (Hildesheim, 2001).

Staatskanzlei , Wissenschaft und Kunst, K6, fol. 33. The Director of the archives, Mraz Gottfried Dr , and his co-worker, Dr Elisabeth Springer, found this letter, which was classed in error under “Kaimarus” rather than “Raimarus”.

Cf. De astronomicis hypothesibus, Fi,r.12, where Ursus responds to the charge of plagiarism in Rothmann's letter of 21 February 1589: “Let it be a theft, but a philosophical one. Learn to look after your property more carefully in future [Sit furtum, sed Philosophicum: Disce in posterum rem tuam custodire]”. Kepler took this, or affected to take it, as an admission of guilt: KGW , xiii, no. 123. 244–5. However, the context makes it clear that Ursus was baiting Tycho, not confessing; and he unambiguously denied the theft elsewhere in De astronomicis hypothesibus: Div,r.28–29.

Cf. De astronomicis hypothesibus, Ciii,r.8–12; Dii,r.15–v.23.

Virgil , Aeneid, i, 604.

Not in Ursus's hand.

“Ursus” written in left-hand margin, not in Ursus's hand.

Underlining not by the same pen as the letter.

On Tycho's counterattack in De astronomicis hypothesibus see Jardine , Kepler's A defence of Tycho, chap. 2; and Launert , Nicolaus Reimers, 285–320.

Letter of Brahe Tycho to Kepler , 28 August 1600: TBOO, viii, 344.1–4; KGW, xiv, no. 173. 148–151.

The inscription reads “D. Levino Hulsio amico singulari devotiss[imus] Autor”. The copy is now at the Forschungs- und Landesbibliothek, Gotha. See Launert , Nicolaus Reimers, 286–8.

Launert , Nicolaus Reimers, 267.

See Volf J. , Geschichte des Buchdrucks in Böhmen und Möhren bis 1848 (Weimar, 1928), 71 and 82–83.

On the circulation of woodblocks among Prague printers of the period see Bohatkova M. , “Book-printing and other forms of publishing in Prague, 1550–1650”, in Fucikovà E. (eds), Rudolf and Prague: The court and the city (London, 1997), 332–9.

On the Prague printing houses see ibid., and Volf, Geschichte des Buchdrucks (ref. 5), 28–96. Volf lists a dozen printing houses active in 1597, and Bohatkova estimates that there were twenty-eight printing houses in the period 1550–1650.

TBOO, viii, 50.32–37.

See List M. and Bialas V. , “Die Coss von Jost Bürgi in der Redaktion von Johannes Kepler”, Abhandlungen der Bayerische Akademie der Wissenschaften: Mathematisch-naturwissenschaftliche Klasse, n.s., cliv (1973), 5–128, pp. 108–9.

TBOO, iv, 6.19–21; mocked by Ursus , De astronomicis hypothesibus, B2,r.3ff.

For mentions of Johannes Trunccius, see Taurellus Nicolaus , Emblemata physico-ethica (Nürnberg, 1602), 44, 90.

De astronomicis hypothesibus, Bi,r.24–25.

I thank Professor Dr Arno Oberschelp of Kiel, who provided me with the crucial clue for this solution.

On Holger Rosenkrantz and his dealings with Tycho, see Thoren V. E. , The Lord of Uraniborg: A biography of Tycho Brahe (Cambridge, 1990), 387–8, 400–2; and Christianson J. B. , On Tycho's island: Tycho Brahe and his assistants, 1570–1601 (Cambridge, 2000), 344–6.

TBOO, viii, 112.27–32. We thank Adam Mosley for bringing to our attention this passage and its possible significance: See Mosley , Bearing the heavens, 173, n.333.

TBOO, viii, 126.21–26.

On Eric Lange and his dealings with Tycho and Tycho's sister, see Christianson , On Tycho's island (ref. 1), chaps. 5–9 and pp. 258–64.

Tycho to Vedel , 18 September 1599, TBOO, viii, 180.40–181.7.

TBOO, viii, 210.7–211.7; KGW, xiv, no. 145. 264–299.

TBOO, viii, 141–4.

KOO, i, 230.55–231.56. Walther's affidavit is to be found in vol. v, 302r–303v, of the Kepler papers at the Academy of Sciences, St Petersburg.

TBOO, viii, 210.35–42; KGW, xiv, no. 145. 291–298.

Plesner K. F. , Bøger og bogsamlere (Copenhagen, 1962), 71.

See Horstbøll H. , The Royal Library over 350 years, ed. by Ømann L. , transl. by Cranfield V. (Copenhagen, 1997). Our thanks to Adam Mosley and Torsten Schlichtkrull, Head of the Department of Conservation at the Danish National Library of Science and Medicine, for information about these matters.

Cf. Ovid , Metamorphoses, vi, 97.

The marks are placed as follows: Aiv,r.23; Aiv,r.39/40; Aiv,v.7,10/11,14; Aiv,v.24,26/7; Bi,r.8/9; Bii,r.28; Bii,v.11; Bii,v.23,27; Biii,r.20; Biii,v.1; Biv,r.11; Div,r.16.

A,r.35; Fiii,v.34.

Aii,r-Bi,r.

Bi,v-Biv,r. The reference is to the grammar of Tycho's and Rothmann's letters in Epistolae astronomicae. As for Zoilus , “He was a sophist of Amphipolis in the time of Ptolemy, famous for this one outrage, that he dared to find fault with Homer, prince of poets, in books written against him”: Stephanus Carolus , Dictionarium historicum, geographicum, poeticum (Paris, 1596), 451v, col. 2.

The reference is to a passage in Tycho's letter to Rothmann of 21 February 1589 in Epistolae astronomicae, in which Tycho had charged Ursus with plagiarism, and specifically with having copied a defective diagram of his hypotheses whilst visiting Hven in the service of Eric Lange in 1584: TBOO, vi, 179.20–180.5.

Aiv,r.22–27.

Cf. Erasmus , Adagia, ii, 1, 1.

Cf. Terence , Phormio, v, 2, 3.

In maps of the period Kattegat is called “sinus Codanus” or “Codanisch Meerbusen”.

This interpretation follows Dreyer J. L. E. , Tycho Brahe (Edinburgh, 1890), 274.

Aiv,v.4–15. Germans criticized by Tycho in Epistolae astronomicae included Rothmann Paul Wittich (see, for example, TBOO , vi, 141.42–142.5) and Ursus himself. In his letter to Rothmann of 14 January 1595 Tycho had violently denounced, without naming, a certain “Scotus” ( Craig John ), who had criticised his views on comets ( TBOO , vi, 315–37): On this attack on Craig see Mosley A. , “Tycho Brahe and John Craig: The dynamic of a dispute”, in Christianson J. R. Hadravova A. Hadrava P. and Šolc M. (eds), Tycho Brahe and Prague: Crossroads of European science (Frankfurt, 2002), 70–83.

That is, Moritz , Landgraf of Hesse-Kassel, to whom Tycho had dedicated his Epistolae astronomicae, and to whom Ursus here dedicates De astronomicis hypothesibus.

Here, as throughout the work, Ursus calls Rothmann , “Rotzmannus”, “Rotz” meaning “snot”.

Bi,r.7–12.

Bii,v. 11–12. Tycho's sensitivity on the issue of the informality of the letters in Epistolae astronomicae is evident from his defence in the preface of their extemporaneous nature and their plain and simple style appropriate to “mathematical truths”: TBOO, vi, 23.6–34 and 28.6–9.

Bii,v.23–30. Geometry and arithmetic were commonly described in the early-modern period as the two wings of astronomy, Plato often being cited as the source. The image is not to be found in Plato or elsewhere in ancient literature. However, in Republic, vii, and more explicitly in Laws, 817, and Epinomis (then attributed to Plato), 990, geometry and arithmetic are presented as prerequisites for the study of astronomy; and Phaedrus, 246, tells of the wings of the soul, lost at birth, that can be recovered by the true philosopher, enabling him to ascend to the Divine. Dr Sachiko Kusukawa has identified a probable source of the image in Melanchthon's In arithmeticen praefatio Georgii Ioachimi Rhetici (1536), in which arithmetic and geometry are identified as the Platonic wings of the soul and as prerequisites for the study of celestial matters. See Bretschneider G. , Philippi Melanthonis opera quae supersunt omnia (Halle, 1843), xi, col. 282.41–43. and col. 288.4–8 and 26–31.

One of the adulatory poems with which Epistolae astronomicae opens is headed “To the most noble man, Tycho Brahe, Prince of the astronomers of our age”: TBOO, vi, 6. 19–21.

Biv,r.9–12.

Tycho to Kepler , 1 April 1598, TBOO , viii, 46.37–40; Tycho to Hayek , 1598, TBOO viii, 56.12–13.

Rollenhagen to Tycho , April 1598, TBOO, viii, 50.36–51.6.

Tycho to Hayek , 1598, TBOO, viii, 56.5–12.

TBOO, viii, 50.32–37.

TBOO, viii, 50.27–51.6. The source of the copy lent by Tycho to Rosenkrantz was noted by Mosley , Bearing the heavens, 173.

See, for example, Shapiro B. J. , A culture of fact (Ithaca, NY, 2000), chap. 1; and Shapin S. , A social history of truth (Chicago, 1994), chap. 1.

Rosen , Three Imperial Mathematicians, 12. For more nuanced accounts of education and learning among the Danish nobility of the period see Andersen B. , Adelig opfostring: Adelsbørns opdragelse i Danmark 1536–1660 (Copenhagen, 1971); Jespersen L. , “Court and nobility in early-modern Denmark”, Scandinavian journal of history, xxvii (2002), 129–42; and Christianson J. R. , “Tycho and Sophie Brahe: Gender and science in the late sixteenth century”, in Christianson (eds), Tycho Brahe (ref. 23), 30–45.

Eiv,r-Fii,v.

Fii,r: 12–20. The mother of Tycho's children, Kirsten Jørgensdatter, not being of noble blood, was his common-law wife. See Thoren , The Lord of Uraniborg (ref. 1), 45–48.

Aiv,r:27–32; Ciiir:3–12; Dii,r:15–Dii,v:23.

Biii,v-Bivr; H3,r-K1,r. On the sixteenth-century development of prosthaphaeretic methods, see von Braunmühl A. , “Zur Geschichte der prosthaphaeretischen Methode in der Trigonometrie”, Abhandlungen zur Geschichte der Mathematik, ix (1899), 17–29, and Thoren V. , “Prosthaphaeresis revisited”, Historia mathematica, xv (1988), 32–39; on their astronomical applications, see Dreyer J. L. E. , “On Tycho Brahe's manual of trigonometry”, Observatory, xxxix (1916), 127–31.