In the same way the imagination may picture a familiar person or thing acting in an unaccustomed manner, the latter having no basis in fact so far as the individual person or thing is concerned, but being warranted by some experience concerning other persons or things. For instance, one may easily form the image of a dog swimming under water like a fish, or climbing a tree like a cat. Likewise, one may form a mental image of a learned, bewigged High Chancellor, or a venerable Archbishop of Canterbury, dressed like a clown, standing on his head, balancing a colored football on his feet, sticking his tongue in his cheek and winking at the audience. In the same way one may imagine a railroad running across a barren desert, or a steep mountain, upon which there is not as yet a rail laid. The bridge across a river may be imaged in the same way. In fact, this is the way that everything is mentally created, constructed, or invented--the old materials being combined in a new way, and arranged in a new fashion. Some psychologists go so far as to say that no mental image of memory is an exact reproduction of the original impression; that there are always changes due to the unconscious operation of the constructive imagination.
The constructive imagination is able to "tear things to pieces" in search for material, as well as to "join things together" in its work of building. The importance of the imagination in all the processes of intellectual thought is great. Without imagination man could not reason or manifest any intellectual process. It is impossible to consider the subject of thought without first regarding the processes of imagination. And yet it is common to hear persons speak of the imagination as if it were a faculty of mere fancy, useless and without place in the practical world of thought.
The imagination is capable of development and training. The general rules for development of the imagination are practically those which we have stated in connection with the development of the memory. There is the same necessity for plenty of material; for the formation of clear and deep impressions and clear-cut mental images; the same necessity for repeated impression, and the frequent use and employment of the faculty. The practice of visualization, of course, strengthens the power of the imagination as it does that of the memory, the two powers being intimately related. The imagination may be strengthened and trained by deliberately recalling previous impressions and then combining them into new relations. The materials of memory may be torn apart and then re-combined and re-grouped. In the same way one may enter into the feelings and thoughts of other persons by imagining one's self in their place and endeavoring to act out in imagination the life of such persons. In this way one may build up a much fuller and broader conception of human nature and human motives.