52 THE GREEK SCHOOL PHILOSOPHY. 



often embarrasses persons on their entrance upon 

 physical speculations, the difficulty of conceiving 

 that up and down are different directions in dif- 

 ferent places, had been completely got over by 

 Aristotle and the Greek philosophers. They were 

 steadily convinced of the roundness of the earth, 

 and saw that this truth led to the conclusion that 

 all heavy bodies tend in converging directions to 

 the centre. And, they added, as the heavy tends 

 to the centre, the light tends to the exterior, 

 " for Exterior is opposite to Centre as heavy is to 

 light 12 ." 



The tendencies of bodies downwards and up- 

 wards, their weight, their fall, their floating or sink- 

 ing, were thus accounted for in a manner which, 

 however unsound, satisfied the greater part of the 

 speculative world till the time of Galileo and Ste- 

 vinus, though Archimedes in the mean time pub- 

 lished the true theory of floating bodies, which is 

 very different from that above stated. Other parts 

 of the doctrines of motion were delivered by the 

 Stagirite in the same spirit and with the same suc- 

 cess. The motion of a body which is thrown along 

 the ground diminishes and finally ceases; the motion 

 of a body which falls from a height goes on becom- 

 ing quicker and quicker ; this was accounted for on 

 the usual principle of opposition, by saying that the 

 former is a violent, the latter a natural motion. 

 And the later writers of this school expressed the 

 12 De Coelo, iv. 4, 



