SKCT. XXXV. 3. DISEASES OF ASSOCIATION. -513 



veflels occafioned by the defect of heat contributes 

 to theincreafe or accumulation of the fenforial pow- 

 er, of irritation, and that both thefe become exerted 

 on fome internal part, which was not rendered tor- 

 pid by the cold which affected the external parts, 

 nor by its aflbciation with them ; or which fooner 

 recovered its fenfibility. This requires further con- 

 fideration. 



4. An example of the fourth mode, or where the 

 primary part of a feniitive affociation of motions 

 may have increafed action, and the fecondary part 

 increafed fenfation, may be taken from the pain of 

 the fhoulder, which attends inflammation of the 

 membranes of the liver, fee Clafs IV. 2. 2. 9. ; in 

 this circumftance fo much fenforial power feems to 

 be expended in the violent actions and fenfations of 

 the inflamed membranes of the liver, that the mem- 

 branes affociatcd with them become quiefcent to their 

 ufual ftirnuli, and painful in coufequence. 



There may be other modes in which the primary 

 and fecondary parts of the train of aflbciated fenii- 

 tive motions may reciprocally affect each other, as 

 may be feen by looking over Clafs IV. in the cata- 

 logue of difeafes ; all which may probably be re- 

 folved into the plus and minus of fenforial power, 

 but we have not yet had fufficient obfervations made 

 upon them with a view to this doctrine. 



III. The aflbciated trains of our ideas may have 

 fympathies, and their primary and fecondary parts 

 affect each other in fome manner fimilar .to thofe 

 above defcribed ; and may thus occafion various cu- 

 rious phenomena not yet adverted to, befides thofe 

 explained in the Sections on Dreams, Reveries, Ver- 

 tigo, and Drunkennefs ; and may thus difturb the 

 deductions of our reafonings, as well as the dreams 

 of our imaginations ; prefent us with falfe degrees 

 of fear, attach unfounded value to trivial circum- 

 itances ; give occafion to our eaily prejudices and 



antipathies ; 



