SECT. XV. CLASSES OF IDEAS. 139 



here to this definition, to determine, how^ fmall 

 the trains muft be, that fhall be called imagi- 

 nation ; and how great thofe, that fhall be called 

 memory, 



Others have thought that the ideas of memory 

 have a greater vivacity than thofe of imagination : 

 but the^ideas of a perfon in fleep, or in a waking 

 reverie, where the trains connected with fenfation 

 are uninterrupted, are more vivid and diftincl: than 

 thofe of memory, fo that they cannot be diflin- 

 guifhed by this criterion. 



The very ingenious author of the Elements of 

 Criticifm has defcribed what he conceives to be a 

 fpecies of memory, and calls it ideal prefence ; but 

 the inftances he produces are the reveries of fenfa- 

 tion, and are therefore in truth connections of the 

 imagination, though they are recalled in the order 

 they were received. 



The ideas connected by aflbciation are in com- 

 mon difcourfe attributed to memory, as we talk 

 of memorandum. rings, and tie a knot on our 

 handkerchiefs to bring fomething into our minds 

 at a diftance of time. And a fchool-boy, who 

 can repeat a thoufand unmeaning lines in Lilly's 

 Grammar, is faid to have a good memory. 

 But thefe have been already fhewn to belong 

 to the clafs of aflbciation j and are termed ideas 

 of fuggeftion. 



II. Laftly, the method already explained of claf- 

 ling ideas into thofe excited by irritation, fenfation, 

 volition, or aflbciation, we hope will be found more 

 convenient both for explaining the operations of 

 the mind, and for comparing them with thofe of 

 the body ; and for the illuflration and the cure of 

 the difeafes of both, and which we fliall here reca- 

 pitulate. 



VOL. I. L i. Irritative 



