SECT. X. 2. 2. MOTIONS. 35 



five or fynchronous a&ions ; thefe become afibciated by habit, 

 -and are then excited together with great facility, and in many 

 initances gain indiffbluble connexions. So the play of puppies 

 and kittens is a reprefentation of their mode of fighting or of 

 taking their prey i and the motions of the mufcles hecefiary for 

 thofe purpofes, become afibciated by habit, and gain a great 

 adroitnefs of action by thefe early repetitions ; fo the motions 

 of the abdominal mufcles, which were originally brought into 

 concurrent action with the protufive motion of the rectum or 

 bladder by fenfation, become fo conjoined with them by habit, 

 that they not only eafily obey thefe fenfations, occafioned by the 

 flimulus of the excrement and urine, but are brought into vio- 

 lent and unreftrainable adlion in the flrangury and tenefmus. 

 This kind of connexion we fhall term fenfitive aiTociation. 



2. So many of our ideas, that have been excited together or 

 in fucceflion by our fenfations, gain fynchronous or fucceflive 

 afTociaticns, that are fometimes ir.difloluble but with life. Hence 

 the idea of an inhuman or difhonourable action perpetually calls 

 up before us the idea of the wretch that was guilty of it. And 

 hence thofe unconquerable antipathies are formed, which fome 

 people have to the fight of peculiar kinds of food, of which in 

 their infancy they have eaten to excefs, or by conflraint. 



III. i. In learning any mechanic art, as mufic, dancing, or 

 the ufe of the fword, we teach many of our mufcles to act to- 

 gether or in fucceflion by repeated voluntary efforts ; which by 

 habit become formed into tribes or trains of aflbciation, and 

 ferve all our purpofes with great facility, and in fome inftances 

 acquire an indifToluble union. Thefe motions are gradually 

 formed into a habit of acHng together by a multitude of repeti- 

 tions, whil ft they are yet feparately caufable by the will, as is 

 evident from the long time that is taken up by children in learn- 

 ing to walk and to fpeak ; and is experienced by every one, 

 when he firft attempts to fkate upon the ice or to fwim : thefe 

 we fhall term voluntary affociations. 



2. All thefe mufcular movements, when they are thus aflbci- 

 ated into tribes or trains, become afterwards not only obedient 

 to volition, but to the fenfations and irritations ; and the fame 

 movement compofes a part of many different tribes or trains of 

 motion. Thus a (ingle mufcle, when it acts in confort with its 

 neighbours on one fide, afiifts to move the limb in one direction ; 

 and in another, when it acts with thofe in its neighbourhood on 

 the other fide ; and in other directions, when it acts feparately 

 or jointly with thofe that lie immediately under or above it ; and 

 all thefe with equal facility after their affociations have been 

 well eftahlifned. 



The 



