OF NATURAL HISTORY. 519 



of their manners, and the extreme chearfulnefs of their difpofi- 

 tions. 



Reaumur, Condillac, and many other philofophers, confider dura- 

 tion as a relative idea, depending on a train of confcious perception 

 and fentiment. It is certain that the natural meafure of time de- 

 pends folely on the fuccefTion of our ideas. Were it poffible for the 

 mind to be totally occupied with a fingle idea for a day, a week, or 

 a month, thefe portions of time would appear to be nothing more 

 than fo many inftants. Hence a philofopher often lives as long in 

 one day, as a clown or a favage does in a week or a month fpent in 

 mental inaftivity and want of thought. 



This fubjefl; fliall be concluded with a fingle remark : If It be true, 

 and we are certain that it is fo in part, that animals of every fpecies, 

 whatever be the real duration of their lives, from a flow or rapid 

 fucceffion of ideas, and perhaps from the comparative intenfity of 

 their enjoyments, live equally long, and enjoy an equal portion of 

 individual happinefs, it opens a wonderful view of the great bene- 

 volence of Nature. To itore every portion of this globe with ani- 

 mal life, She has amply peopled the earth, the air, and the waters. 

 The multifarious inhabitants of thefe elements, as to the adtuai du- 

 ration of their lives, are extremely diverfified. But, by variation of 

 forms, of magnitude, of rapidity of ideas, of intenfity of pleafures, 

 and, perhaps, of many other circumftances, She has conferred upon, 

 the whole nearly an equal portion of happinefs. 



CHAP. 



