SECT.V. SENSORIAL FACULTIES. 35 



VOLITION is an exertion or change of the central 

 parts of the fenforium, or the whole of ^it, termi- 

 nating in fome of thofe extreme parts of it, which 

 refide in the mufcles or organs of fenfe. 



ASSOCIATION is an exertion or change of fome 

 extreme part of the fenforium refiding in the muf- 

 cles or organs of fenfe, in confequence of fome an- 

 tecedent or attendant fibrous contractions. 



3. Thefe four faculties of the animal fenforium 

 may at the time of their exertions be termed mo- 

 tions without impropriety of language ; for we 

 cannot pafs from a ftate of infenfibility or inaction 

 to a ftate of fenfibility or of exertion without fome 

 change of the fenforium, and every change includes 

 motion. We fhall therefore fometimes term the 

 above defcribed faculties fenforial motions to diftin- 

 guifli them from fibrous motions ; which latter ex- 

 preffion includes the motions of the mufcles and or- 

 gans of fenfe. 



The adive motions of the fibres, whether thofe 

 of the mufcles or organs of fenfe, are probably 

 fimple contractions ; the fibres being again elongat- 

 ed by antagonifl mufcles, by circulating fluids, or 

 fometimes by elaftic ligaments, as in the necks of 

 quadrupeds. The feniorial motions, which confti- 

 tute the fenfations of pleafure or pain, and which 

 conftitute the fenfations of pleafure or pain, and 

 which conftitute volition, and which caufe the fi- 

 brous contractions in confequence of irritation or 

 of aflbciation, are not here fuppofed to be fluctua- 

 tions or refluctuations of the fpirit of animation ; 

 nor are they fuppofed to be vibrations or revibrati- 

 ons, nor condenfations or equilibrations of it; but 

 to be changes or motions of it peculiar to life. 



SECT. 



