Crüger to Müller, Easter Monday 1620
Peter Crüger, “Crüger to Müller, Easter Monday 1620,” Nova Kepleriana 4, 1620, 106–107, transcribed in Plain Old Text, https://sources.vjbe.net/stable/c2nge.
Nova Kepleriana 4 1620, p. 106–107 Summary
Part of Die Keplerbriefe auf der Nationalbibliothek und auf der Sternwarte in Paris
Crüger rejects Kepler's theory of straight-line comet paths because it assumes the earth's annual motion, mocks the 'rabid leaps' it implies, and finds the *Astronomia nova* and *Harmonice mundi* hard to follow.
Source: Peter Crüger's letter to Philipp Müller of Easter Monday 1620, written at Danzig after he had received Kepler's three books on comets (Augsburg, 1619). He rejects Kepler's straight-line paths for comets, because they assume the earth's annual motion, and finds the Astronomia nova and the Harmonice mundi hard going. The original is in the Bibliothèque de l'Observatoire, Paris (B, 1, 9; 89, 9. B. 24). Printed in extracts in Nova Kepleriana 4, ed. Walther von Dyck and Max Caspar, Abhandlungen der Bayerischen Akademie der Wissenschaften, Math.-naturw. Abteilung 31, no. 1 (Munich, 1927), 106–107.
Transcribed from: the page images of the 1927 printing.
Only the Latin is given; the editors’ German commentary and notes are left out. The 1927 edition prints only extracts. Each paragraph below is one of its extracts, and the omission marks (…) are the editors’. Spaced type, which the editors used for emphasis, is given in italics.
English translation of the Latin extracts printed in Nova Kepleriana 4 (1927), made for Plain Old Text. Each paragraph translates the corresponding extract of the original; the omission marks (…) are the 1927 editors’. Italics follow the editors’ emphasis.
Libri Keppleriani in tempore advenerunt, sed tamen adhuc titulum Cometae abs te promissum expecto. Magnas et officiosas habeo gratias.
Kepler’s books arrived in good time, but I am still waiting for the title page of the Comet that you promised me. I am greatly and dutifully obliged to you.
Libri hujus Autoris Cometici ad stabiliendum motum Cometarum rectilineum exingeniossissime sunt conscripti. Sed tamen huic motui Cometarum subscribere non possum. Causae mihi duae sunt. Una, quod primum omnium assumit Terrae motum annuum tamquam evidenter demonstratum, de quo tamen adhuc sub judice lis est. Ego utut motum terrae diurnum credo, non tamen annuum animo meo inducere possum. …
This Author’s books on comets are written most ingeniously to establish that comets move in straight lines. Even so, I cannot subscribe to this motion of comets, and I have two reasons. The first is that before anything else he assumes the earth’s annual motion as clearly proved, when the case is still before the judge. Though I believe in the earth’s daily motion, I cannot bring myself to accept the annual one. …
Altera causa, quae motum Cometarum rectilineum amplecti prohibet, est, quod nullo modo trajectoria repraesentare possit motum Cometae proprium, qui supra semicirculum excrescat. …
The other reason that keeps me from embracing the straight-line motion of comets is that a straight path can in no way represent a comet’s own motion where it grows beyond a semicircle. …
Theoremata Keppleri citata mirabilem Cometae motum supponunt nec unquam de ullo Cometa vel somniatum vel auditum. Theorema XXI satis obscurum nullo illustravit diagrammate; ego tamen obscuritate superata diagramma eius, omnibus eius verbis conveniens, tibi hic una mitto. Perpende quaeso diligenter et vide modo rabiosos Cometae saltus, modo inertes stationes. Quis (malum!) unquam ab aevo condito tale quicquam vidit vel audivit? Triumphum igitur ante victoriam canere videtur Kepplerus. … Sed de his desino, veritus ne Te, Keppleri observantissimum, hac censura offendam. Quicquid feci, veritatis Astronomiae studiosus feci: quam tibi credo prae omnibus amicis amicam.
The theorems of Kepler cited above suppose a marvellous motion of the comet, never dreamt of or heard of in any comet. Theorem XXI, obscure enough, he illustrated with no diagram; but I have overcome its obscurity, and I send you a diagram of it here, agreeing with every word of his. Weigh it carefully, I beg you, and see the comet’s rabid leaps one moment and idle standstills the next. Who (confound it!) since the world was made ever saw or heard of such a thing? Kepler seems, then, to sing the triumph before the victory. … But I shall stop here, fearing to offend you, who think so highly of Kepler, with this criticism. Whatever I have done, I have done as a student of astronomical truth, which I believe is a friend to you above all your friends.An echo of the proverb amicus Plato, sed magis amica veritas: Plato is a friend, but truth a greater one.
… Opus eius de Marte oppido requirit hominem ab omni alia cogitatione liberum nec id uno die sed integro anno, donec apprehendi per omnia possit. Ausim dicere, virum studiosissime obscuritati et perplexitati dedisse operam …
… His work on Mars demands a man free of every other thought, and that not for one day but for a whole year, until it can be grasped throughout. I would dare to say that the man has worked most zealously at being obscure and intricate …
Harmoniam Mundi Kepplerianam nondum attente pervolvi. Videtur hoc opus aeque obscurum ac Martiale …
Kepler’s Harmony of the World I have not yet read through attentively. This work seems as obscure as the one on Mars …