508 ADDITIONS. 



men to free themselves from the prejudices of the senses, and to inter- 

 pret their testimony in such a manner as to conceive the sphericity of 

 the earth. It is natural that they should have stopped at this point, 

 before putting the earth in motion in space." 



Some of the expressions which have been understood as describing 

 a system in which the Sun is the centre of motion, do really imply 

 merely the Sun is the middle term of the series of heavenly bodies 

 which revolve round the earth : the series being Moon, Mercury, Venus, 

 Sun, Mars, Jupiter, Saturn. This is the case, for instance, in a passage 

 of Cicero's Vision of Scipio, which has been supposed to imply (as I 

 have stated in the History), that Mercury and Venus revolve about, 

 the Sun. 



But though the doctrine of the diurnal rotation and annual revolu- 

 tion of the earth is not the doctrine of Pythagoras, or of Philolaus, or 

 of Plato, it was nevertheless held by some of the philosophers of anti- 

 quity. The testimony of Archimedes that this doctrine was held by 

 his contemporary Aristarchus of Samos, is unquestionable ; and there 

 is no reason to doubt Plutarch's assertion that Seleucus further en- 

 forced it. 



It is curious that Copernicus appears not to have known any thing 

 of the opinions of Aristarchus and Seleucus, which were really antici- 

 pations of his doctrine ; and to have derived his notion from passages 

 which, as I have been showing, contain no such doctrine. He says, 

 in his Dedication to Pope Paul III., " I found in Cicero that Nicetas 

 [or Hicetas] held that the earth was in motion : and in Plutarch I 

 found that some others had been of that opinion ; and his words I will 

 transcribe, that any one may read them : ' Philosophers in general 

 hold that the earth is at rest. But Philolaus the Pythagorean teaches 

 that it moves round the central fire in an oblique circle, in the same 

 direction as the Sun and the Moon. Heraclides of Pontus and Ec- 

 phantus the Pythagorean give the earth a motion, but not a motion 

 of translation ; they make it revolve like a wheel about its own centre 

 from west to east.' " This last opinion was a correct assertion of the 

 diurnal motion. 



The Eclipse of Thales. 



" The Eclipse of Thales" is so remarkable a point in the history of 

 astronomy, and has been the subject of so much discussion among as- 

 tronomers, that it ought to be more especially noticed. The original 



