OF NATURAL HISTORY. 519 



« "When compared to this, all other trees are but children of 

 < of the foreft*/ 



From the fa£ls which have been enumerated, it appears, 

 that all animals, as well as vegetables, have ftated periods of 

 exiftence, and that their diflblution is uniformly accomplifli- 

 ed by a gradual hardening and deficcation of their conftituent 

 parts. No art, no medicine, can retard the operations of 

 Nature. It is, therefore, the wifdom and the duty of every 

 •human being to fail down the irrefiftible current of Nature 

 with all poffible tranquility and refignation. Life, whether 

 fhort or long, whether fortunate or unfortunate, when the 

 fatal period arrives, is of little confequence to the individual. 

 Society, knowledge, virtue, and benevolence, are our only 

 rational enjoyments, and ought to be cultivated with dili- 

 gence. 



With regard to animals in general, the actual duration 

 of their lives is very different. But the comp^irative Ihort- 

 nefs or length of life, in particular animals, probably de- 

 pends on the quicknefs or llownefs of the ideas which pafs 

 in their minds, or of the impreflions made upon their fenfes. 

 A rapid fucceflion of ideas or impreflions makes time feem 

 proportionally long. There is likewife a connedlion between 

 the quicknefs and flownefs of ideas, and the circulation of 

 the blood. A man whofe pulfe is flow and fluggifli, is ge- 

 nerally dull and phlegmatic. Raife this fame man^s pulfe 

 with wine, or any other exhilirating ftimulus, and you im- 

 mediately quicken his fenfations, as well as the train of his 

 ideas. In all young animals, the circulation of the blood is 

 much more rapid than after they have acquired their full 

 growth. Young animals, accordingly, are frolickfome, 

 vivacious, and happy. But, when their growth is completed, 

 the motion of blood is flower, and their manners, of courie, 

 are more fedate, gloomy, and ponfive. Another circum- 



* Ibid page 500. 



