Sect. X. 2. 2. MOTIONS, 35 



five or fynchronous alliens ; thefe become a/Tociated by habit, 

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

 inftances gain indifTolubie connexions. So the play of puppies 

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

 taking their prey ; and the motions of the mufcles necefTary for 

 thofe purpofes become afTociated 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 protrufive 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 

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

 lent and unreftrainable action in the ftrangury and tenefmus. 

 This kind of connexion we mail term fenfitive afTociation. 



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

 in fucceffioxi by our fenfations, gain fynchronous or fuccefhve 

 afTociarions, that are fometimes indifTolubie 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 feme 

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

 their infancy they have eaten to excefs or by conftraint. 



III. 1. 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 fucceffion by repeated voluntary efforts ; which by 

 habit become formed into tribes or trains of afTociation, and 

 ferve all our purpofes v/ith great facility, and in fome inftances 

 acquire an indifTolubie union. Thefe motions are gradually 

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

 tions, whilft 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 Ikate upon the ice or to fwim : thefe 

 we (hall term voluntary alTociations. 



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

 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 flngle mufcle, when it acts in con fort with its 

 neighbours on one fide, afTifts 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 afibciations have been 

 well eftablifhed, 



The 



