280 PREFACE TO THE 



That Bacon was acquainted with his writings we can 

 hardly believe ; they bear so directly on the questions 

 which he has discussed that he could scarcely have 

 neglected to notice them, had he known them even by 

 report. In the very first page of Kepler's great work 

 we find a quotation from Peter Ramus, declaring that 

 he would resign his professorship in favour of any one 

 who should produce an astronomy without hypotheses. 

 To this Kepler subjoins an apostrophe to Ramus, tell- 

 ing him that it is well that death had relieved him of 

 the necessity of redeeming his pledge, and vindicating 

 Copernicus from the charge of having explained the 

 phenomena of astronomy by unreal hypotheses. The 

 same subject is resumed in the preface, and elsewhere 

 throughout the book. Again, in another point of view, 

 it makes Bacon's complaints that astronomers cling su- 

 perstitiously to perfect circles appear somewhat out of 

 date, to find that before the time at which he wrote the 

 man who confessedly both by his genius and his official 

 position stood at the head of the astronomers of Europe 

 and, so to speak, represented them, had succeeded in 

 saving the phenomena more accurately than had been 

 done before, by means of ellipses. A great change had 

 just taken place ; two most remarkable laws, the foun- 

 dations of modern physical astronomy, had just been 

 propounded, namely the law of elliptic motion, and 

 that of the equable description of areas ; and the whole 

 state of the question with respect to the truth or false- 

 hood of the Copernican system was thus changed. In 

 truth this system was inextricably connected not only 

 with Kepler's results, but with his method. In his 

 dedication to the Emperor he says, " Locum (that is, 

 the place of Mars) indagine cinxi, curribus magnae 



