We see in this experimentally studied case some of the conditions that favor invention. Good physical condition, freshness, mastery of the subject, striving for some result, and "hopefulness". Now, what is that last? Confidence, enterprise, willingness to "take a chance", eagerness for action and readiness to break away from routine? Some of this independent, manipulating spirit was probably there.
A soldier, so wounded as to paralyze his legs but capable of recovery by training, had advanced far enough to hobble about with a cane and by holding to the walls. One morning, feeling pretty chipper, he took a chance and left the wall, cutting straight across the room; and getting through without a fall, was naturally much encouraged and [{519}] maintained this advance. This might be called invention; it was breaking away from what had become routine, and that is the essential fact about the inventive reaction. This playful spirit of cutting loose, manipulating, and rearranging things to suit yourself is certainly a condition favorable to invention. It does not guarantee a valuable invention, but it at least helps towards whatever invention the individual's other qualifications make possible.
Another condition favorable to invention is youth. Seldom does a very old person get outside the limits of his previous habits. Few great inventions, artistic or practical, have emanated from really old persons, and comparatively few even from the middle-aged. On the other hand, boys and girls under eighteen seldom produce anything of great value, not having as yet acquired the necessary mastery of the materials with which they have to deal. The period from twenty years up to forty seems to be the most favorable for inventiveness.
Imagination Considered in General
Finally, we must return to the question of definition or general description that was left open near the beginning of the chapter. There seem to be two steps in the inventive response, one preliminary, the other strictly inventive. The preliminary step brings the stimuli to bear, and invention is the response that follows.
Typically, the preliminary stage consists in recall; and association by similarity, bringing together materials from different past experiences, is very important as a preliminary to invention. Facts recalled from different contexts are thus brought together, and invention consists in a response to such novel combinations of facts. The two steps in invention are, first, getting a combination of stimuli, and second, responding to the combination.
Sometimes it has been said that imagination consists in putting together material from different sources, but this leaves the matter in mid-air; recall can bring together facts from different sources and so afford the stimulus for an imaginative response, but the response goes beyond the mere togetherness of the stimuli. Thinking of a man and also of a horse is not inventing a centaur; there is a big jump from the juxtaposition of the data to the specific arrangement that imagination gives them. The man plus the horse may give no response at all, or may give many other responses besides that of a centaur; for example, a picture of the man and the horse politely bowing to each other. The particular manipulation, or imaginative response, that is made varies widely; sometimes it consists in taking things apart rather than putting them together, as when you imagine how a house would look with the evergreen tree beside it cut down; always it consists in putting the data into new relationships.
Imagination thus presents a close parallel to reasoning, where, also, there are two stages, the preliminary consisting in getting the premises together and the final consisting in perceiving the conclusion. The final response in imagination is in general like that in reasoning; both are perceptive reactions; but imagination is freer and more variable. Reasoning is governed by a very precise aim, to see the actual meaning of the combined premises; that is, it is exploratory; while imagination, though it is usually more or less steered either by a definite aim or by some bias in the direction of agreeable results, has after all much more latitude. It is seeking, not a relationship that is there, but one that can be put there.