Ms] The Harmony of the " II 'or Id and the Epitome 191 



Mysterium Cosmographicum, and most of the rest is filled 

 with worthless analogies between the proportions of the 

 solar system and the relations between various musical 

 scales. 



He is bold enough to write down in black and white the 

 " music of the spheres " (in the form shewn in fig. 62), while 

 the nonsense which he was capable of writing may be 

 further illustrated by the remark which occurs in the same 

 part of the book : " The Earth sings the notes M I, F A, M I, 

 so that you may guess from them that in this abode of ours 

 Misery (miserid) and FAmine (fames) prevail." 



145. The Epitome of the Copernican Astronomy, which 

 appeared in parts in 1618, 1620, and 1621, although there 

 are no very striking discoveries in it, is one of the most 

 attractive of Kepler's books, being singularly free from the 

 extravagances which usually render his writings so tedious. 

 It contains within moderately short compass, in the form 

 of question and answer, an account of astronomy as known 

 at the time, expounded from the Coppernican standpoint, 

 and embodies both Kepler's own and Galilei's latest dis- 

 coveries. Such a text-book supplied a decided want, and 

 that this was recognised by enemies as well as by friends 

 was shewn by its prompt appearance in the Roman Index 

 of Prohibited Books (cf. chapter vi., 126, 132). The 

 Epitome contains the first clear statement that the two 

 fundamental laws of planetary motion established for the 

 case of Mars ( 141) were true also for the olher planets 

 (no satisfactory proof being, however, given), and that they 

 applied also to the motion of the moon round the earth, 

 though in this case there were further irregularities which 

 complicated matters. The theory of the moon is worked 

 out in considerable detail, both evection (chapter n., 48) 

 and variation (chapter in., 60; chapter v., in) being 

 fully dealt with, though the "annual equation" which 

 Tycho had just begun to recognise at the end of his life 

 (chapter v., in) is not discussed. Another interesting 

 development of his own discoveries is the recognition 

 that his third law of planetary motion applied also to 

 the movements of the four satellites round Jupiter, as 

 recorded by Galilei and Simon Marius (chapter vi., 118). 

 Kepler also introduced in the Epitome a considerable 



