176 SENSATION, 



* colour* or the word 'sound.' Yet it is immediately seen 

 that the idea of each of those metals is made up of the 

 separate ideas of several sensations : colour, hardness, 

 extension, weight. Those ideas, however, present them- 

 selves in such intimate union, that they are constantly 

 spoken of as one, not many. We say, our idea of iron, 

 our idea of gold ; and it is only with an effort that reflect- 

 ing men perform the decomposition." 



Ideas fuse themselves in this manner into clusters, or 

 complex ideas, because, being only repetitions or weak 

 copies of sensations, they are reproduced in the same order 

 as the sensations. And the Sensations in question habitu- 

 ally occur in clusters because the * external objects ' to 

 which they correspond usually impress the organism sim- 

 ultaneously through different senses. Thus it happens, 

 according to the law above cited from Hartley, that when 

 any one constituent of a natural cluster of sensations 

 comes within the range of the corresponding sense organs 

 of an animal, the other possible impressions composing the 

 cluster (and representing the organism's knowledge of the 

 external object) become simultaneously nascent in memory, 

 so that the object is perceived or recognized. If in a dai'k 

 room my hand comes upon an orange or upon a book, 

 either of these sensations of touch will immediately fuse 

 with nascent ideas of other possible sensations from the 

 same object (whichever it may be) so that this object is 

 perceived as a present external reality. This, then, is the 

 nature of the process known as Perception : in which we 

 have a present sensation linking itself indissolubly by 



* association ' with a complex idea derived from our • past 

 experiences with similar objects. It is not, as James Mill 

 implies, the appreciation of a mere ' cluster of sensations.' 



Thus it happens that an object is recognized imme- 

 diately or intuitively, not so much by the mere single or 



