366 SenfiUe Impreflions mot evanefcent. [Book IXi 



colifequcnce of the application of its nofe to the teat of 

 its mother, they attribute its capacity for executing a 

 function, in which fo many mufcles are employed, to 

 a connection originally exifting between the nerves 

 of its nofe and thofe which belong to the organs em- 

 ployed in fucking. The moft complex inftinctive 

 actions of animals, according to thefe philofophers, 

 may be explained on the fame hypothefis. 



The qualities of bodies, as perceived by one fenle, 

 are very frequently connected with others perceived in 

 the fame bodies by the other fenfes : thus, apparent 

 uncvennefs of furface, is united with a roughnefs to 

 the touch ; apparent vibration, with found ; and there 

 is a certain analogy between the odours and taftes of 

 many bodies. Thefe conclufions, however, are to be 

 referred to our previous experience, and by no means 

 authorize us to think that there is any fimilitude in the 

 mode of perception between the fenfes of feeing and 

 hearing, feeing and feeling, or tailing and fmelling. It 

 is faid, that there have been perfons who could diftin- 

 guifh colours by the fenfe of feeling j but if they did, 

 it muft evidently have been from fome difference of 

 roughnefs, fmoothnefs, &c. refulting from the mate- 

 rials employed in colouring, and not from any pro- 

 perty inherent in the different colours as objects of 

 fight. 



It is ordained by our Creator, for the moft impor- 

 tant purpofes, that our fenfations mould not be too 

 evanefcent j and it requires fome time after one im- 

 prelTion is made on an organ of fenfe, before that organ 

 can receive another. This is proved by a very fimple 

 and decifive experiment. All of us h&ve probably 

 obferved, when a ftick lighted at one end, or a coal, 

 is whirled round with a certain degree of velocity, that 

 the whole circle which it performs appears equally illu- 

 minated, 



