PHYSIOLOGY. 47 



is generally faithful to such associations ; but it is more or less 

 so in different persons, according to the number and import- 

 ance of the relations marked, according to the frequency of the 

 repetition of the sensations, and the marking of their relations ; 

 and according to the different states of the brain, very little 

 known. " That the difference of memory depends upon the 

 state of our corporeal part, is undoubted. Children are a re- 

 markable instance of this : they do not soon acquire the faculty 

 of memory. Haller has put it at five years ; but, without ascer- 

 taining the precise period, we may say that it is only by the fre- 

 quent repetition, and some advance in age, that they acquire any 

 power of remembering. In like manner, every body in the de- 

 cline of life, comes to be sensible of some failure of memory ; 

 and before our intellectual operations are obliterated, this is an- 

 nounced by the failure of memory, which happens to every man 

 universally, and much about the same period ; so that in in- 

 fancy and in old age, there is a state of our corporeal organs, 

 which is not so well suited to the exercise of this faculty. We 

 have also organic affections of the brain obliterating memo- 

 ry. Thus, there are instances of persons in fever losing every 

 thing laid upon their brain, as Haller speaks, so that they had to 

 betake themselves again to learn the use of letters. And no- 

 thing is so common as that the memory is obliterated in palsy, 

 and similar affections ; so that there can be no doubt that, how- 

 ever the difference of memory may be referred to mental causes, 

 it is, in many more instances, a corporeal affection." 



LXIX. Imagination seems always to depend upon internal 

 causes that is, upon causes acting in the brain. 



LXX. Memory and imagination renew distinctly the ideas 

 of seeing and hearing only. All others are renewed imperfectly, 

 or not at all ; but all others maybe associated (LXVIII.) with 

 the sensations or ideas of seeing and hearing, so that these be- 

 come signs of the others. " This is a proposition that may be 

 referred to every man's own experience, whether he can recall 

 the taste of any thing, as well as he can recall the image which 

 he received by sight, or the sound which he received by hear- 

 ing." The memory, in renewing these signs, so far renews the 

 idea belonging to them as to renew their several associations 

 and relations ; to renew, in some degree, the pleasure or pain 



