When Kepler did the work that led to his epoch making Astronomia nova he had recently inherited both the title and data of Tycho’s position of Imperial Mathematicus in Prague. He was determined to use this data in order to prove his own version of the heliocentric hypothesis; the result as is well known was his first two laws of planetary motion. His ambition to use Tycho’s data to prove Copernicus right and Tycho wrong did not go down well with Tyco’s other ex-assistants, whom Kepler referred to as the Tychonics. The leader of Kepler’s opposition was Tycho’s long-term chief assistant Christian Longomontanus (1562 – 1647), meanwhile Professor for Mathematics in Copenhagen. The two of them carried out their dispute in a correspondence in which they pulled no punches.
Longomontanus wrote to Kepler 6th May 1604:
These and perhaps all other things that were discovered and worked out by Tycho during his restoration of astronomy for our eternal benefit, you, my dear Kepler, although submerged in shit in the Augean stable of old, do not scruple to equal. And you promise your labor in cleansing them anew and even triumph, as if we should recognise you as Hercules reborn. But certainly no one does, and prefers you to such a man, unless when all of it has been cleaned away, he understands that you have substituted more appropriate things in the heaven and in the celestial appearances. For in this is victory for the astronomer to be seen, in this, triumph. On the other hand, I seriously doubt that such things can ever be presented by you1. However, I am concerned lest this sordid insolence of yours defile the excellent opinion of all good and intelligent men about the late Tycho, and become offensive.
Kepler responded early in 1605:
The tone of your reference to my Augean stable sticks in my mind. I entreat you to avoid chicanery, which is wont to be used frequently with regard to unpopular things. So that you might see that I have in mind how the Augean stable provided me with the certain conviction that I have not discredited astronomy – although you can gather from the present letter – I will use it with the greatest possible justification. But it is to be used as an analogy, not for those things that you or Tycho were responsible for constructing – which either blinded by rage or perverted by malice you quite wrongfully attributed to me – but rather in the comparison of the ancient hypotheses with my oval path2. You discredit my oval path. I hold up to you the hundred-times-more-absurd spirals of the ancients (which Tycho imitated by not setting up anything new but letting the old things remain). If you are angry that I cannot eliminate the oval path, how much more ought you to be angry with the spirals, which I abolished. It is as though I have sinned with the oval I have left, even though to you all the rest of the ancients do not sin with so many spirals. This is like being punished for leaving behind one barrow full of shit although I have cleaned the rest of the Augean stables. Or in your sense, you repudiate my oval as one wagon of manure while you tolerate the spirals which are the whole stable, to the extent that my oval is one wagon. But it is unpleasant to tarry in rebutting this most manifest slander.
1) This is of course exactly what Kepler did achieve with his Astronomia nova.
2) The oval orbit for Mars was a intermediate stage on Kepler’s route to the ellipse and was responsible for his famous complaint to David Fabricius (1564 – 1617) in a letter from 4th July 1603: I lack something: knowledge of the geometrical generation of the oval path […] If the figure were a perfect ellipse…!
All quote are taken from James R. Voelkel, The Composition of Kepler’s Astronomia Nova, Princeton University Press, Princeton and Oxford, 2001.
P. S. Whilst on the subject of Tycho and Kepler, Darin at PACHS has written a nice post on the pointlessness of the exhumation of Tycho’s corpse in order to determine his cause of death. In his post he mentions Joshua and Anne-Lee Gilder’s, Heavenly Intrigue: Johannes Kepler, Tycho Brahe, and the Murder Behind One of History’s Greatest Scientific Discoveries a book that claims that Kepler murdered Tycho in order to steal his data. If you haven’t already wasted your time in reading this book don’t bother, it’s shit!