Sect. V. i. SENSORIAL FACULTIES. 21 



SECT. V. 



OF THE FOUR FACULTIES OR MOTIONS OF THE SENSCRIUM. 



I. Four fenforial powers. 2. Irritation, fen/at ion, volition, ajfoci- 

 ation defined. 3. Senforial motions difiingufhed from fibrous mo- 

 tions. 



1. The fpirit of animation has four different modes of ac- 

 tion, or in other words the animal fenforium poifeiTes four dif- 

 ferent faculties, which are oecafionally exerted, and caufe all 

 the contractions of the fibrous parts of the body. Thefe are 

 the faculty of caufing fibrous contractions in confequence of 

 the irritations excited by external bodies, in confequence of the 

 fenfations of pleafure or pain, in confequence of volition, and in 

 confequence of the aflbciations of fjftppus contractions with oth- 

 er fibrous contractions, which precede or accompany them. 



Thefe four faculties of the fenforium during their inactive ftate 

 are termed irritability, fenfibility, voluntarity, and afibciability ; 

 in their active ftate they are termed as above, irritation, fenfa- 

 tion, volkion, aflbciation. 



2. Irritation is an exertion, or change of fome extreme 

 part of the fenforium refiding in the mufcles or organs of fenfe, 

 in confequence of the appulfes of external bodies. 



Sensation is an exertion or change of the central parts of the 

 fenforium, or of the whole of it, beginning at fome of thofe ex- 

 treme parts of it, which refide in the mufcles or organs of fenfe. 



Volition is an exertion or change of the central parts of the 

 fenforium, or of the whole of it, terminating in fome of thofe ex- 

 treme 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 mufcles or organs of fenfe, in 

 confequence of fome antecedent or attendant fibrous contrac- 

 tions. 



3. Thefe four faculties of the animal fenforium may at the 

 time of their exertions be termed motions 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 {hall therefore fometimes term the above defcribed faculties 

 fenfo rial motions to diftinguifh them from fibrous motions ; 



which latter exprcflion includes the motions of the mufcles and 

 organs of fenfe. 



The active motions of the fibres, whether thofe of the mufcles 



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