PRELUDE TO THE EPOCH OF COPERNICUS. 261 



favor of the geocentric doctrine, that the heaviest body must be in the 

 centre, it was maintained, as a leading recommendation of the oppo- 

 site opinion, that it placed the Fire, the noblest element, in the Centre 

 of the Universe. The authority of mythological ideas was called in 

 on both sides to support these views. Numa, as Plutarch 3 informs us, 

 built a circular temple over the ever-burning Fire of Vesta ; typifying, 

 not the earth, but the Universe, which, according to the Pythago- 

 reans, has the Fire seated at its Centre. The same writer, in another 

 of his works, makes one of his interlocutors say, " Only, my friend, do 

 not bring me before a court of law on a charge of impiety ; as Cle- 

 anthes said, that Aristarchus the Samian ought to be tried for im- 

 piety, because he removed the Hearth of the Universe." This, how- 

 ever, seems to have been intended as a pleasantry. 



The prevalent physical views, and the opinions concerning the 

 causes of the motions of the parts of the universe, were scarcely more 

 definite than the ancient opinions concerning the relations of the four 

 elements, till Galileo had founded the true Doctrine of Motion. 

 Though, therefore, arguments on this part of the subject were the 

 most important part of the controversy after Copernicus, the force of 

 such arguments was at his time almost balanced. Even if more had 

 been known on such subjects, the arguments would not have been 

 conclusive : for instance, the vast mass of the heavens, which is com- 

 monly urged as a reason why the heavens do not move round the 

 earth, would not make such a motion impossible ; and, on the other 

 hand, the motions of bodies at the earth's surface, which were alleged 

 as inconsistent with its motion, did not really disprove such an opinion. 

 But according to the state of the science of motion before Copernicus, 

 all reasonings from such principles were utterly vague and obscure. 



We must not omit to mention a modern who preceded Copernicus, 

 in the assertion at least of the heliocentric doctrine. This was Nicholas 

 of Cusa (a village near Treves), a cardinal and bishop, who, in the 

 first half of the fifteenth century, was very eminent as a divine and 

 mathematician ; and who in a work, De Docta lynorantia, propounded 

 the doctrine of the motion of the earth ; more, however, as a paradox 

 than as a reality. We cannot consider this as any distinct anticipation 

 of a profound and consistent view of the truth. 



We shall now examine further the promulgation of the Heliocentric 

 System ly Copernicus, and its consequences. 



6 De Facie in Orle Luntz, 6. 



