DISUOVERIES^N THE CELESTIAL SPACES. 313 



the earth is immovably fixed in a central point, while the sun 

 revolves around it as a circling- planet, attended by two satel- 

 lites, Mercury and Venus. Such a view of the structure of 

 the world might, indeed, prepare the way for that of the cen- 

 tral force of the sun. There is, however, nothing in the Al- 

 magest, or in the works of the ancients generally, or in tho 

 work of Copernicus, De Revolutionibus, which justifies the 

 assertion so confidently maintained by Gassendi, of the perfect 

 resemblance existing between the system of Tycho Brahe and 

 that which has been ascribed to Apollonius of Perga. After 

 Bockh's complete investigation, nothing further need be said 

 of the confusion of the Copernican system with that of the 

 Pythagorean, Philolaiis, according to which, the non-rotating 

 earth (the Antichthon or opposite earth, being not in itself a 

 planet, but merely the opposite hemisphere of our planet) 

 moves like the sun itself round the focus of the world — the 

 central fire, or vital flame of the whole planetary system. 



The scientific revolution originated by Nicolaus Copernicus 

 has had the rare fortune (setting aside the temporary retro- 

 grade movement imparted by the hypothesis of Tycho Brahe) 

 of advancing without interruption to its object — the discovery 

 of the true structure of the universe. The rich abundance of 

 accurate observations furnished by Tycho Brahe himself, the 

 zealous opponent of the Copernican system, laid the founda- 

 tion for the discovery of those eternal laws of the planetar} 

 movements which prepared imperishable renown for the name 

 of Kepler, and which, interpreted by Newton, and proved to 

 be theoretically and necessarily true, have been transferred 

 into the bright and glorious domain of thought as the intellect- 

 ual recognition of nature. It has been ingeniously said, al- 

 though, 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.*" 



ed mathematically the assumption of the retrogressions of the planets 

 under the idea of a revolution round the sun, without adding any thing 

 definite and general as to the truth of this assumption. The difference 

 of the Apollonian system, described by Gassendi, from that of Tycho, 

 would only be, that the latter likewise explained the inequalities of the 

 movements. The remark of Robert Small, that the idea which forms 

 the basis of Tycho's system was by no means unfamiliar to the mind 

 of Copernicus, but had rather served him as a point of transition to his 

 own system, appears to me well founded." 



* Schubert, Astronomie, th. i., s. 124. In the Philosophy of the In' 

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

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

 Vol. II.— -O 



