OF NATURAL HISTORY. 177 



the number of impulfes on the papillae. "When a man is pinched 

 with hunger, the fight or idea of palatable food raifes the whole pa- 

 pillae of his tongue and ftomach. From this circumflance he is 

 highly regaled by eating. But, if he eats the fame fpecies of food 

 when his ftomach is lefs keen, the pleafure in the one cafe is not to 

 be compared with what is felt in the other. The caufe is obvious : 

 His defire was not fo urgent; the object:, of courfe, was lefs allu- 

 ring ; and therefore he was more remifs in ereding his papillae, or 

 in putting them in a tone fuited to fuch eminent gratification. 



The fame obfervations are applicable to difagreeable or painful 

 objedts of contaft. If the hand is laid upon a gritty ftone, or a 

 piece of rufty iron, the feeling is difagreeable ; but if it is frequently 

 rubbed upon the furface of thefe bodies, the feeling becomes infuf- 

 ferably irkfome. 



It is by the fenfe of touch that men, and other animals, are enabled 

 to perceive and determine many qualities of external bodies. By this 

 fenfe we acquire the ideas of hardnefs and foftnefs, of roughnefs and 

 fmoothnefs, of heat and cold, of preflure and weight, of figure, and 

 of diftance. The fenfe of touch is more uniform, and liable to few- 

 er deceptions, than thofe of fmelling, tafting, hearing, and feeing ; 

 becaufe, in examining the qualities of objeds, the bodies themfelves 

 muft be brought into adual contadt with the organ, without the in- 

 tervention of any medium, the variations of which might miflead 

 the judgment. 



OF SEEING. 



OF all the fenfes, that of feeing is unqueftionably the nobleft, the 



moft refined, and the moft extenfive. The ear informs us of the 



I Z t exiftence 



