DISCOVERIES IN THE CELESTIAL SPACES. 695 



by Newton, and proved to be theoretically ana necessarily 

 true, have been transferred into the bright and glorious 

 domain of thought, as the intellectual recognition of nature. 

 It has been ingeniously said, although, perhaps, with too 

 feeble an estimate of the free and independent spirit which 

 created the theory of gravitation, that. " Kepler wrote a code 

 -of laws, and Newton the spirit of those laws.*" 



The figurative and poetical myths of the Pythagorean and 

 Platonic pictures of the universe, changeable as the fancy 

 from which they emanated,f may still be traced partially 

 reflected in Kepler ; but while they wanned and cheered his 

 often saddened spirit, they never turned him aside from his 

 earnest course, the goal of which he reached in the memorable 

 night of the 15th of May, 1618, twelve years before his 

 death. \ Copernicus had furnished a satisfactory explana- 



* Schubert, Astronomic, th. i. s. 124. In the Philosophy of tht 

 Inductive Sciences, vol. ii. p. 282. Whewell, in his Inductive Table of 

 Astronomy, has given an exceedingly good and complete view of the 

 astronomical contemplation of the structure of the universe, from the 

 earliest ages to Newton's system of gravitation. 



t Plato in the Phcedrus adopts the system of Philolaus ; but in the 

 Timceus, that according to which the earth is immoveable in the centre, 

 and which was subsequently called the Hipparchian, or the Ptolemaic. 

 (Bbckh, De Platonico systemate ccdestium globorum, et de vera indole 

 astronomice Philolaicce, pp. xxvi.-xxxii. ; the same author in the Phi- 

 lolaos, s. 104-108. Compare also Fries, Geschichte der Philosophic, 

 bd. i. s. 325-347, with Martin's Etudes sur Timee, t. ii. pp. 64-92.) The 

 astronomical vision, in which the structure of the universe is shrouded, 

 at the end of the Book of the Republic, reminds us at once of the inter- 

 calated spherical systems of the planets, and of the concord of tones, 

 " the voices of the Sirens moving in concert with the revolving spheres." 

 (See on the discovery of the true system of the universe, the fine and 

 comprehensive work of Apelt, Epochen der Gescli. der Metucheit, bd. i. 

 1845, s. 205-305, and 379-445.) 



Kepler, Harmonices Mundi, libri quinque, 1619, p. 189. " On the 

 <th of March, 1618, it occurred to Kepler, after many unsuccessful 

 attempts, to compare the squares of the times of revolution of the 

 planets with the cubes of the mean distances ; but he made an error in 

 his calculations, and rejected this idea. On the 15th of May, 1618, he 

 again reverted to it, and calculated correctly. The third law of Kepler was 

 now discovered." This discovery, and those related to it, coincide with 

 the unhappy period when this great man, who had been exposed from earlj 

 childhood to the hardest blows of fate, was striving to save from the toi- 

 ture and the stake his mother, who, at the age of seventy years, in a 

 trial for witchcraft, which lasted six years, had been accused of poiaoa 



