THE GOLDEN AGE OF GREECE 73 



But the mathematical doctrines concerning the parts and ele- 

 ments of the Universe are put forward by Plato, not so much as as- 

 sertions concerning physical facts, of which the truth or falsehood is 

 to be determined by a reference to nature herself. They are rather 

 propounded as examples of a truth of a higher kind than any refer- 

 ence to observation can give or can test, and as revelations of prin- 

 ciples such as must have prevailed in the mind of the Creator of the 

 universe ; or else as contemplations by which the mind of man is to 

 be raised above the region of sense, and brought nearer to the Divine 

 Mind. Whewcll. 



PLATONIC COSMOLOGY. The spherical figure of the earth was 

 now generally accepted in Greece, and the older fanciful cos- 

 mogonies gradually disappeared. To Plato, whose interest in 

 physical science was indeed but secondary, the earth was a 

 sphere at the centre of the universe, requiring no support. He 

 supposes the distances of the heavenly bodies to be proportional 

 to the numbers: Moon 1, Sun 2, Venus 3, Mercury 4, Mars 8, 

 Jupiter 9, Saturn 27, these numbers being obtained by com- 

 bining the arithmetic and geometric progressions, 1, 2, 4, 8 and 

 1, 3, 9, 27. 



Plato accepts as a principle that the heavenly bodies move with 

 a uniform and regular circular motion ; he then proposes to the mathe- 

 maticians this problem : ' What are the uniform and regular circular 

 motions which may properly be taken as hypotheses in order that 

 we may save the appearances presented by the planets ? ' 



His general conception of the world as expressed in the Timaeus 

 and in the tenth book of the Republic is decidedly mystical. 

 In the latter a soul returning to its body after 12 days in the other 

 world relates its experiences in imaginative language : 



Everyone had to depart on the eighth day and to arrive at a 

 place on the fourth day after, whence they from above perceived ex- 

 tended through the whole heaven and earth a light as a pillar, mostly 

 resembling the rainbow, only more splendid and clearer, at which 

 they arrived in one day's journey ; and there they perceived in the 

 neighborhood of the middle of the light of heaven, the extremities of 



