ASSOCIATION OF IDEAS. This is a phrase of great importance in the philosophy of the human mind, as expressing the most pervading fact at the foundation of our intelli gence. By giving, therefore, a somewhat full exposition of this subject, we are able to explain, at once, a considerable number of the complex phenomena of mind in a more satisfactory way than by treating the several phenomena separately. What is meant by association of ideas, is familiarly illustrated by such occurrences as the following: When we see the sky becoming overcast, we think of rain as about to follow, the notion of rain not having previously been present to our mind. When we hear the church-bells, we arc apt to think of the crowds in the street, or of some of the other circumstances of public worship. When we pass a house, we are reminded of its occupier; and meeting a person we know, we may be carried in thought to his office, and from that to other persons holding the same office, and so on. If an object is before my eyes, as a moun tain, I am said to receive an impression or sensation of it, in consequence of the actual presence of the thing; but it is possible for me to remember the mountain, or to have an idea of it, when far away from the reality, in which case there must be some power in the mind itself, different front the susceptibility to present objects, a power of retain ing, reviving, or resuscitating those states at first induced by contact with the actual. Besides the sights, and sounds, and touches caused by contact with real things, we are greatly occupied with sights, sounds, and touches remembered, anticipated, or imagined, which is to live in a world of ideas; and it is in this world that the process termed asso ciation has its sphere. When all idea is brought before the mind without its original, as when I picture to my mind the late duke of Wellington, the circumstance is owing to the mention of his name, or of sonic incident connected with him; and my remembrance of his personal appmfance, aS1 haVeseeir hithwhen alive, is' said to be the result of an association existing in my mind between two ideas, so that the one is able to recall or restore the other. The association between names and things comprehends one of the most extensive applications of the power in question.
The circumstances under which one idea brings forward another into the view are principally these two—viz., first, previous proximity; and second, likeness. The terms " contiguity" and " similarity" are used in mental philosophy to express them. The first is exemplified in the examples of association given above; for in most of those it will be found that the conjoined notions have been frequently in the view at thd same time, in consequence of which they have, as it were, grown together, or become part of the same whole. Thus, we have often noticed the darkened sky followed by a shower; the two facts have occupied the attention simultaneously, and, in virtue of some power belonging to our mental framework, they have cohered into an inseparable couple or aggregate in the mind. This is proximity, or contiguity. When one idea suggests another which was never in company with it before, it is generally through the force of some likeness between the two. I meet an old man in the street with a very peculiar face, which reminds me of the bust of Socrates. These two things had never accompanied one ano ther in my mind before, and therefore it could not be the force of proximity that made the second to arise at the instigation of the first; but there was a certain amount of like ness or similarity between the old man's features and the features of Socrates, as repre sented to us in the bust; and it is a fact of our constitution, no less certain and no less important than the foregoing, that in cases where something now before the mind has a strong cast of resemblance to something formerly observed or conceived by us, but not at present thought of in any way, the present is apt to recall that past idea, whatever it may be. By the force of likeness, the traveler in new countries is constantly reminded of the scenes and objects familiar to him, and so is induced to draw comparisons between the one and the other. Identification and comparison both imply that things are brought together by virtue of their similarity, they not having been in company before. The principle of proximity operates most in memory, habit, and routine; similarity has to do with invention and originality, and is essential to the processes of reason and imagina tion.