THE UNIVERSE. DISCOVERIES IN THE CELESTIAL SPACES. 311 



appreciation of the free, great, and independent spirit 

 which conceived the theory of gravitation, " Kepler wrote a 

 book of laws, Newton the spirit of the laws/' 



The figurative poetic myths of the Pythagorean and 

 Platonic pictures of the universe, ( 476 ) variable as the 

 imagination from which they had their birth, still found 

 a partial reflex in Kepler; they warmed and cheered his 

 often saddened spirits, but they did not divert him from 

 the earnest path which he steadfastly pursued, and of which 

 he reached the goal, ( 477 ) 12 years before his death, on the 

 memorable night of the 15th of May, 1618. Copernicus 

 had afforded a sufficient explanation of the apparent 

 revolution of the heaven of the fixed stars, by the diurnal 

 rotation of the Earth around her axis ; and by the annual 

 movement round the sun, had given an equally perfect 

 solution of the most striking movements of the planets 

 (their retrogressions and stationary appearances), and had 

 thus found the true cause of what is called the " second 

 inequality of the planets." The first inequality, the non- 

 uniform movement of the planets in their orbits, he left 

 unexplained. True to the ancient Pythagorean principle of 

 the inherent perfection of circular movements, Copernicus, in 

 his structure of the universe, needed to add to the " excen- 

 tric" circles having unoccupied centres, some of the epicycles 

 of Apollonius of Perga. Bold as was the path struck out, 

 men could not free themselves at once from all earlier views. 



The equal distance at which the fixed stars continue from 

 each other, whilst the whole heavenly vault moves from East 

 to West, had led to the representation of a firmament, 

 a solid crystal sphere, in which Anaximenes, (who was 

 perhaps not much later than Pythagoras), imagined the stars 



