THE THEORY OF GRAVITATION. 145 



the case of a body near the earth. All the atoms coming toward the 

 body from the direction of the earth would be cut oft* by it, while from 

 all other directions the body would be subjected to uninterrupted bom- 

 bardment. Consequently there would be a resultant motion of the 

 earth, that is in the line of diminished resistance, and this resultant 

 motion would be exactly the same as if the bombarding atoms all con- 

 verged toward the earth's center instead of moving fortuitously. 



VII. 



The Epicureans would have even seized with avidity upon this occa- 

 sion to give an air of disorder to the primitive movements of the uni- 

 verse. For this would accord the better with their system of the ori- 

 gin of things (otherwise sufficiently absurd and impious) that there was 

 do appearance of parallelism, perfect or imperfect, whereas all tend- 

 ency to parallelism would appear to be the result of some particular 

 design, and consequently to indicate the operation of some intelligent 

 being. 



VIII. 



I speak of disorder in connection with primitive movements only. 

 The resultant motion of bodies having inertia would be directed toward 

 the center of our globe with great exactness, in consequence of the 

 combination of a vast number of impulses in different directions. For 

 it is a well-known result of the doctrine of chances that minor irregu- 

 larities, when in great number, mutually compensate each other 

 exactly, so that each several inequality becomes imperceptible in its 

 effect upon the resultant. 



IX. 



Still another consideration would have led the atomists to make this 

 same modification of the direction of motion of the gravitational atoms. 

 All will agree with me that they were certain to have met with one or 

 other of these two objections or to have themselves raised them. As the 

 earth revolves without cessation about the sun, 1 the hypothesis that 



1 Democritus was a century and a half later than Pythagoras, who had secretly 

 taught the revolution of the earth. He might even have seen Philolaus who more 

 openly proclaimed it, and Timaeus who appears to have had the same belief. He 

 ought also to have been informed of the opinion of the Pythagoreans upon the sub- 

 ject, for Heraclides had been of this sect before he listened to Plato and Aristotle, 

 and he maintained at least that the earth rotated about its center. According to the 

 report of Diogenes, Laertius. and of Porphyry, Democritus had attended the teach- 

 ing of the Pythagoreans; and besides, the Eleatic sect (if one may credit Strabo) 

 was nothing but an offshoot of the Italic. Finally, the atomists, following Demo- 

 critus, would have had opportunity to be even better instructed than he in regard 

 to the earth's motion. For this doctrine was supported by a multitude of philoso- 

 phers of all countries, among whom the principal names, in addition to those already 

 cited, are Archimedes and Nicetas, of Syracuse ; Aristarchus and Clean thus, of Samos ; 

 Architas, of Tarento; Seleucus, Eophautus, and even (according to Theophrastus) 

 Plato in his later years. 

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