320 LAPLACE. 



action of Saturn, forming a total of 618 days, or more 

 than a year and eight months. 



Never did a question of astronomy excite a more in- 

 tense, a more legitimate curiosity. All classes of society 

 awaited with equal interest the announced apparition. 

 A Saxon peasant, Palitzch, first perceived the comet. 

 Henceforward, from one extremity of Europe to the 

 other, a thousand telescopes traced each night the path 

 of the body through the constellations. The route was 

 always, within the limits of precision of the calculations, 

 that which Clairaut had indicated beforehand. The pre- 

 diction of the illustrious geometer was verified in regard 

 both to time and space : astronomy had just achieved a 

 great and important triumph, and, as usual, had destroyed 

 at one blow a disgraceful and inveterate prejudice. As 

 soon as it was established that the returns of comets 

 might be calculated beforehand, those bodies lost for ever 

 their ancient prestige. The most timid minds troubled 

 themselves quite as little about them as about eclipses of 

 the sun and moon, which are equally subject to calcula- 

 tion. In fine, the labours of Clairaut had produced a 

 deeper impression on the public mind than the learned, 

 ingenious, and acute reasoning of Bayle. 



The heavens offer to reflecting minds nothing more 

 curious or more strange than the equality which subsists 

 between the movements of rotation and revolution of our 

 satellite. By reason of this perfect equality the moon 

 always presents the same side to the earth. The hemi- 

 sphere which we see in the present day is precisely that 

 which our ancestors saw in the most remote ages ; it is 

 exactly the hemisphere which future generations will 

 perceive. 



The doctrine of final causes which certain philosophers 



