46 GREAT MEN OF SCIENCE 



Linz, where he remained fourteen years. Here he married 

 for the second time; but in this period also he suffered much, 

 for example, the witch trial in which evilly-disposed persons 

 had involved his mother. He hastened to her and saved her 

 by an effective defence when she was about to be tortured. 

 His work in Linz was his most comprehensive book, the 

 Harmomces Muridi, and he also completed there the Rudolfine 

 Tables. The latter then remained for a century the founda- 

 tion of all planetary calculations. Of the five books of the 

 H ar mo flic es {which, appeared in 1619), the fifth has become 

 of undying importance by its announcement of the third law 

 of planetary motion, which here appears joined with the two 

 first laws. Kepler discovered it from the figures given 

 by Copernicus and Tycho for their observations; he describes 

 it himself as being the result of 17 years of work. His 

 own high valuation of this part of the Harmonices is shown 

 by the following sentence in the preface: 'I shall cast the 

 die and write a book, whether for the present day or for 

 posterity - it is the same to me. Let it await its readers for a 

 century -God himself has waited for his interpreter for six 

 thousand years.' 



High enthusiasm for his work and its results enable him 

 again and again to rise confidently above the confusion of his 

 external life. 



The remaining books of the Harmonices deal with 

 geometry, music, the theory of harmony, and with the con- 

 nection of the latter, and also of human life, with the 

 motions of the planets. Here much seems strange to us 

 to-day; but this feeling is only justified by our having come 

 to see clearly that the relation between spirit and matter 

 cannot be of so simple a character as was imagined in Kepler's 

 time. But Kepler's search for such relations was unjustly 

 despised; for they must exist, since spirit and matter are 

 actually connected with one another in the processes of life. 

 If to-day few traces of this search are to be found in works of 



