PHILOSOPHY, MENTAL. 



relations, either in itself, or in its effects 

 on the mind, with another idea already 

 on the mind, the later is recalled by 

 the former, and becomes connected with 

 it : and the association thus produced 

 is subject to the same laws with those 

 formed, owing to the contiguity in the 

 times of the reception of the ideas. 



RESPECTING THE COMPOSITION OF IDEAS. 



53. Another grand law, or mode of 

 operation, of the associative power is 

 that by which simple ideas are formed 

 into compound, or complex ideas; in 

 other words, more generally, by which 

 simple sensorial changes are combined 

 and blended together. In the conside- 

 ration of this law, we shall derive most 

 of our statements from those of Hartley, 

 divesting them, however, of those peculia- 

 rities of expression, which depend for 

 their correctness upon the truth of the 

 positions, that the medullary substance 

 of the brain is the sensorium, and that 

 sensorlal changes are vibrations of the 

 medullary substance. In order to ex- 

 plain this law of association, it is $ne- 

 cessary to take a view of the modes in 

 which simple ideas, or ideas of sensation, 

 may be associated. 



Case 1. Let the sensation A be often 

 associated with each of the sensations B, 

 C, D, &c. ; that is, ai certain times with 

 B, at certain other times with C, and so 

 on : it is evident from what has been be- 

 fore stated ( 21.) that A, when produced 

 alone, will raise a, b, c, d, &c. (the simple 

 ideas of sensation corresponding respec- 

 tively with A, B, C, D, 8tc,) altogether, 

 and consequently will associate them to- 

 gether. If a, If, c, d, Sec. are distinct in 

 all their parts, then, in the first instance 

 they will be merely connected, so as to 

 make a group (which may be represent- 

 ed by rt-f-6-f-c-{-f/,) but if they are not 

 distinct in their parts, they more or less 

 run into each other, so as to form a com- 

 plex cluster, (which may be represented 

 by abed.) Now the more frequently the 

 group a-\-b-^-c-\-d, &.c. occurs in connec- 

 tion, the more closely the single ideas are 

 united ; and unless any one has a peculiar 

 degree of vividness, they will by degrees 

 appear to the mind as one idea ; and un- 

 less the notice of the mind is particularly 

 directed to the circumstance, that it is com- 

 posed of parts, it appears as much a single 

 idea as originally each of the parts would 

 have done, if the attention had been di- 

 rected to them singly. Again, the more 

 the cluster abed, &c. occurs in combination 



the more completely the parts coalesce, 

 so that by degrees they form a complex 

 idea, the parts of which are scarcely dis- 

 tinguishable. 



54. Case 2. If the sensations A, 13, C, D, 

 &.C. be associated together, according to 

 various combinations of twos, or even of 

 threes, fours, &.c. then will A raise up />-f- 

 c-f- d, &.c. ; also I? will raise up a-\-c-\-d t 

 &.c. ; and compound or complex ideas 

 will be formed of those combinations, pre- 

 cisely as was before stated in the case of 

 sensations singly associated with another 

 sensation. It may happen indeed in both 

 cases, that A may raise a particular idea, 

 as 6, preferably to any of the rest, in con- 

 sequence of its being more frequently 

 associated with b, or of the greater novel- 

 ty of the impression of the corresponding 

 sensation, B, rendering it more vivid, or 

 of some tendency of the sensorium to ex- 

 cite b, or of some other cause ; and in 

 like manner that B may raise c or d pre- 

 ferably to the rest. However, all this 

 will at last be over-ruled by the recur- 

 rence of the associations, so that any one 

 of the sensations will excite the ideas of 

 the rest at the same instant, and there- 

 fore associate them together. 



55. Case 3. Let A, B, C, D, &c. repre- 

 sent succcessive sensations (occurring in 

 contiguous, successive instants,) A will 

 raise b, c, d, &c. B will raise c, d, &c. : 

 and though the ideas do not rise precise- 

 ly in the same instant, yet they come 

 nearer and nearer together than the sen- 

 sations did in their original impression ; 

 so that these ideas are at last associated 

 synchronously, as they were from the first 

 successively. 



56. Case 4. All compound impressions, 

 A -f B + C -f D, &c. or A BCD, Etc. (ac- 

 cording as they are received by different 

 organs, or the same) after sufficient repe- 

 tition, leave behind their compound ideas 

 d _|_ b -j- c -f- d, &c. or abed, &c which re- 

 cur every now and then by means of sen- 

 sations, or ideas, with which the whole 

 compound, or any one or more of the parts, 

 A, B, C, D, &c. have been associated. 

 Now in these recurrences of compound 

 ideas, the parts are further associated, 

 and more intimately united to one another, 

 agreeably to what was observed above, so 

 as to form a compound or complex idea, 

 which shall appear to the mind as one single 

 idea. As the same causes produce the re- 

 currence of the compounded ideas in what- 

 soever way the union was first produced, 

 the same remark may be made under each 

 of the cases as have been under this and 



