ch. vni.] ORGANIZATION OF THE SCIENCES. 201 



moving masses; for lie tells us that while astronomy has 

 been a science since the time of Hipparchos, physics first 

 became a science in the days of Galileo. The slightest con- 

 sideration will show us that this apparent confirm" tion of 

 Comte's views rests upon a verbal ambiguity. For what por- 

 tion of astronomical phenomena had been generalized as early 

 as the time of Hipparchos ? Simply the statical or geo- 

 metrical portion, namely, the apparent motions of the planets, 

 the great achievement of Hipparchos having been the con- 

 struction of the theory of epicycles and eccentrics, whereby 

 to formulate these motions. It is needless to add that all the 

 geometrical data used in making this generalization had been 

 obtained from the previous observation of terrestrial pheno- 

 mena. And what portion of physics was it which was not 

 generalized till the time of Galileo ? It was the dynamical 

 portion, since statics had been erected into a science by 

 Archimedes, who lived just a century before Hipparchos. 

 By comparing the statical part of astronomy with the dyna- 

 mical part of physics, Comte finds it quite easy to establish 

 the precedence of the former. Unfortunately, such pre- 

 cedence is not what the argument requires, though it is all 

 that can be established. If we compare like orders of pheno- 

 mena, we shall see at once that it was physics which pre- 

 ceded astronomy. Dynamical astronomy became a science 

 only with the discovery of the law of gravitation ; and this 

 law was not discovered, nor could it have been discovered, 

 until after the leading generalizations of terrestrial dynamics 

 had been established. For, as Mr. Spencer observes, " What 

 were the laws made use of by Newton in working out his 

 grand discovery ? The law of falling bodies, disclosed by 

 Galileo; that of the composition of forces, also disclosed by 

 Galileo ; and that of centrifugal force, found out by Huy- 

 ghens — all of them generalizations of terrestrial physics. . . . 

 Had M. Comte confined his attention to the things and dis- 

 regarded the words, he would have seen that before mankind 



