MENTAL SYSTEMS 35
the instinctive, and not only extends but is systematized ; for experience can not extend beyond its rudimentary stages, can not become varied, rich and adequate to the needs of grow ing life except as new individual experiences are treasured up in the organism, represented in mental images, and or ganized into systems.
I. PROCESSES OF ORGANIZATION
i. Concepts built up in various fields of experience. As pointed out in the preceding chapter, if our images repre sented original experience in all its details, and, if when revived, appeared in the accidental and often haphazard order of the original sensations they would often form only a heterogeneous multitude, having no relations of prac tical value among themselves, and the very purpose of thought would be defeated. They must be sorted out, asso ciated together, fused into types or moulded into concepts which represent whole masses of particular and concrete experiences, in order that they may become effective tools for our use. If when the word " tree " is mentioned there were called up all the detailed images of all the trees one s eyes had ever rested upon, the consciousness would be swamped by a mass of useless particulars. As a matter of fact, they are all fused and fashioned into an image which represents all of them and is easily recalled and used. As one s experience extends, the concept will be found to rep resent a class of objects which at the same time forms part of a larger class and divides up into a number of sub-classes. For instance, the concept " tree " is found to belong to a much larger class of objects, plants or vegetables; and at the same time to include a number of varieties of trees. Thus the mental organization goes on by a process of broader generalization, on the one hand ; and discrimination and division on the other. At the same time concepts are forming in adjacent fields of experience, and these fields of experience are coming to be related to one another. While the child is acquiring the notion " tree," he is also forming
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