776 OF THE FUNCTIONS OF THE NERVOUS SYSTEM. 



the formation of such a connection between two or more ideas, that the con- 

 sciousness of one tends to bring the other also before the consciousness ; or, in 

 other words, each tends to suggest the other. Certain laws of Association, 

 expressive of the conditions under which this connection is formed, and the 

 mode in which it acts, have been laid down by Psychologists ; and these may 

 be concisely stated as follows : 1. Law of Contiguity. Two or more states of 

 consciousness, habitually existing together or in immediate succession, tend to 

 cohere, so that the future occurrence of any one of them is sufficient to restore 

 or revive the other. Tt is thus (to take a simple illustration) that the im- 

 pressions made upon our sensational consciousness by natural objects, which are 

 usually received through two or more senses at once, are compacted into those 

 aggregate notions, which, however simple they may appear, are really the result 

 of the intimate combination of many distinct states of ideation. Thus our 

 notion of the form of an object is made up of separate notions derived from the 

 visual and muscular senses respectively; our notion of the character of its 

 surface, from the combination of impressions received through the visual and 

 tactile senses ; and with both of these our notion of color, as in the case of an 

 orange, may be so blended, that we do not readily conceive of its characteristic 

 form and surface, without also having before our minds the hue with which 

 these have been always associated in our experience. So, again, the external 

 aspect of a body suggests to our minds its internal arrangement and qualities, 

 such as we have before found them invariably to be ; thus, to use the preceding 

 illustration, the shape and color of the orange bring before our consciousness its 

 fragrant odor and agreeable taste, as well as the internal structure of the fruit. 

 And our notion of an orange must be considered as the aggregate of all the 

 preceding ideas. Not only the different ideas excited by one object, but those 

 called up by objects entirely dissimilar, may thus come to be associated, provided 

 that the mind has been accustomed to the presentation of them in frequent 

 contiguity one with the other. Such conjunctions may be natural, that is, they 

 may arise out of the " order of nature;" or they may be artificial, being due to 

 human arrangements ; all that is requisite is, that they should have sufficient 

 permanence and constancy to habituate our minds to the association. Of this 

 law of contiguity, moreover, we have a most important example in the association 

 which the mind early learns to form between successive events, so that, when the 

 first has been followed by the second a sufficient number of times to form the 

 association, the occurrence of the first suggests the idea of the second ; if that 

 idea be verified by its occurrence, a definite expectation is formed ; and if that 

 expectation be unfailingly realized, the idea acquires the strength of a belief. 

 And thus it is that we come to acquire that part of the notion of " cause and 

 effect," which consists in invariable and necessary sequence (see p. 34), and to 

 form our fundamental conception of the invariability of Nature. It is by the 

 same kind of operation, again, that we come to employ words as the symbols of 

 ideas, for the convenience of intercommunication and reference ( 790); a 

 certain number of repetitions of the sound, concurrently with the sight of the 

 object, or the suggestion of the notion of that object, being sufficient to establish 

 the required relation in our minds. Of the large share which this kind of 

 action takes in the operations of Memory and Recollection, evidence will be 

 presently given. The readiness with which these Associations are formed 

 varies greatly in different individuals and at different periods of life. As a 

 general rule, it is far greater during the period of growth and development, than 

 after the system has come to its full maturity; and remembering that those new 

 functional relations between other parts of the Nervous system, which give rise 

 to the " secondarily-automatic" movements or acquired instincts, are formed 

 during the same period, it seems fair to surmise that the substance of the 

 Cerebrum groics to the conditions under which it is habitually exercised ; and 



