160 COSMICAL ARRANGEMENTS. 



law of universal gravitation, that the planets do 

 not execute their movements in this insulated 

 and independent manner. Each of them is acted 

 on by the attraction of all the rest. The Earth is 

 constantly drawn by Venus, by Mars, by Jupiter, 

 bodies of various magnitudes, perpetually chang- 

 ing their distances and positions with regard to 

 the Earth ; the Earth in return is perpetually 

 drawing these bodies. What, in the course of time, 

 will be the result of this mutual attraction ? 



All the planets are very small compared with 

 the sun, and therefore the derangement which 

 they produce in the motion of one of their 

 number will be very small in the course of one 

 revolution. But this gives us no security that 

 the derangement may not become very large in 

 the course of many revolutions. The cause acts 

 perpetually, and it has the whole extent of time 

 to work in. Is it not then easily conceivable 

 that in the lapse of ages the derangements of the 

 motions of the planets may accumulate, the orbits 

 may change their form, their mutual distances 

 may be much increased or much diminished? 

 Is it not possible that these changes may go 

 on without limit, and end in the complete sub- 

 version and ruin of the system ? 



If, for instance, the result of this mutual gravi- 

 tation should be to increase considerably the ex- 

 centricity of the earth's orbit, that is to make it 

 a longer and longer oval ; or to make the moon 



