XX INTRODUCTORY OBSERVATIONS. 



man might be born without any of the fenfes, we 

 cannot figure how he could have mind, or be ca- 

 pable of diflinguifhing obje£ls. But there are ma- 

 ny animals which want fome of the known fenfes, 

 and are flill capable of volition, choice, and feveral 

 of thofe fenfations which we afcribe to the 

 ?noft perfecl. It is not evident that they labour 

 under much inconvenience, where certain organs 

 are entirely wanting, or derive equivalent advan- 

 tage, where they aboundi The variety of organs 

 is more effential than the number. — The flight 

 of an infed is as rapid with two wings as with 

 four : vifion is as acute with two eyes as with 

 eight : progreflion is as quick with fix or eight 

 legs as with an hundred. Indeed it is diiiieult 

 to fay what is the ufe of fuch a redundancy of 

 organs, at leaft, if we judge from fimple appear- 

 ances. Some animals, which have only fix legs 

 at firft, acquire an additional pair every year of 

 their lives. There is one fpecies with eight legs, 

 when full grown, in which the third pair is want- 

 ing at firft ; and another, with fix pair originally,, 

 and a feventh is afterwards acquired. 



More than five fenfes may exift ; nor is there 

 any abfolute necefTity for limitation to that num- 

 ber. In various animals, there may be others 

 fo complicated or uncommon, as to be totally 

 incomprehenfible by the human mind ; and they 



may 



