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.

{520}

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