SECT. X. 3. ASSOCIATE MOTIONS, 5$ 



in the mufcles of the arm in. moving the \vind- 

 lafs of an air-pump ; and the ilownefs of thofe 

 mufcular movements, that have not been aflbciated 

 by habit, may be experienced by any one, who 

 fliall attempt to faw the air quick perpendicularly 

 with one hand, and horizontally with the other at 

 the fame time. 



3. In learning every kind of fcience we volunta- 

 rily affociate many tribes and trains of ideas, which 

 afterwards are ready for all the purpofes either of 

 volition, fenfation, or irritation ; and in (bine in- 

 ftances acquire indiffolubie habits of acting together, 

 fo as to affect our reafonjng, and influence our ac- 

 tions. Hence the neceflity of a good education. 



Thefe affociate ideas are gradually formed into 

 habits of acting together by frequent repetition, 

 while they are yet feparately obedient to the will; 

 as is evident from the difficulty we experience 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 com- 

 pofes a part of many different tribes and trains of 

 ideas. So the firnple idea of vvhitenefs compofes a 

 part of the complex idea of mow, milk, ivory j 

 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, in which this letter 

 enters. 



The numerous trains of thefe affociated ideas are 

 divided by Mr. Hume Into three claffes, which he 

 has termed contiguity, caufation, and refemblance. 

 Nor mould we wonder to find them thus connected 

 together, fmce it is the bufinefs of our lives to dif- 

 pofe them into thefe three claffes ; and we become 

 valuable to ourfelves and our friends, as we fucceed 



in 



