3 6 ASSOCIATE MOTIONS. Sect. X. 3. 3, 



The facility, with which each mufcle changes from one aflo- 

 ciated tribe to another, and that either backwards or forwards, 

 is well obfervable in the mufcles of the arm in moving the wind- 

 lafs of an air-pump ; and the flownefs of thofe mufcular move- 

 ments, that have not been affociated by habit, may be experi- 

 enced by any one, who (hall attempt to faw the air quick per- 

 pendicularly with one hand, and horizontally with the other at 

 the fame time. 



3. In learning every kind of fcience we voluntarily aflbciate 

 many tribes and trains of ideas, which afterwards are ready for 

 all the purpofes either of volition, fenfation, or irritation ; and 

 in feme inftances acquire indiffoluble habits of acting together, 

 fo as to affect, our reafoning, and influence our actions. Hence 

 the neceffity of a good education. 



Thefe aflbciate ideas are gradually formed into habits of act- 

 ing together by frequent repetition, while they are yet feparately 

 obedient to tht will ; as is evident from the difficulty we experi- 

 ence in gaining fo exact an idea of the front of St. Paul's church, 

 as to be able to delineate it with accuracy, or in recollecting a 

 poem of a few pages. 



And thefe ideas, thus affociated into tribes, not only make up 

 the parts of the trains of volition, fenfation, and irritation ; but 

 the fame idea compofes a part of many different tribes and trains 

 of ideas. So the fimple idea of whitenefs compofes a part of the 

 complex idea of fnow, milk, ivory ; and the complex idea of the 

 letter A compofes a part of the feveral affociated trains of ideas 

 that make up the variety of words, into which this letter enters. 



The numerous trains of thefe affociated ideas are divided by 

 Mr. Hume into three claffes, which he has termed contiguity, 

 eaufation, and refemblance. Nor mould we wonder to find 

 them thus connected together, fince it is the bufinefs of our 

 lives to difpofe them into thefe three claffes 5 and we become 

 valuable to ourfelves and our friends, as we fucceed in it. Thofe 

 who have combined an extenfive clafs of ideas by the contiguity 

 of time or place, are men learned in the hiflory of mankind, and 

 of the fciences they have cultivated. Thofe who have connect- 

 ed a great clafs of ideas of refemblances, poffefs the fource of 

 the ornaments of poetry a<M oratory, and of all rational analo- 

 gy. While thofe who have connected great claffes of ideas of 

 eaufation, are furnifhed with the powers of producing effects. 

 Thefe are the men of active wifdem, who lead armies to victory, 

 and kingdoms to profperity •, or difcover and improve the fci- 

 ences, which meliorate and adorn the condition of humanity. 



SECT. 



