A short definition of Visualization by Roberto Assagioli:
TECHNIQUE OF VISUALIZATION
The general purpose of evoking the imagination has already been discussed. The great importance and paramount value of visualization is that it constitutes the necessary preliminary training for, and furthers the purpose of, other important techniques. For instance, the dear visualization of the “ideal model” implies the ability to visualize. Therefore we will deal first with the technique of visualization; also in therapy we should at the outset explain to the patient the various uses of this technique; for example, that it is essential for the clear picture of the “ideal model” which is the goal of the psychosynthesis.
Visualization helps greatly in, and is one of the most suitable techniques for, the training of concentration in its first stages. Further, visualization helps, or rather implies and requires the use of the will, and some of the exercises of evocative imagination which are described below, under Procedure, constitute a class of the so-called “useless exercises” which we have mentioned in dealing with the will.
Another purpose of visualization is to offer a starting point for or incentive to creative imagination; and finally it makes possible the effective use of symbolic visualization which will be dealt with when we take up specifically the technique of the use of symbols.
In the Rationale on Imagination we mentioned the fundamental law that every image has a motor-tendency. Now we add something more: that every movement requires a previous image of the movement to be executed. This has been proved by certain forms of aphasia or rather one specific form of aphasia, the cause of which is the loss of the evocation of the image of the words to be pronounced. In short: visualization is a necessary stage for action.
In order to clarify our discussion, let us consider the differences between reproductive imagination and creative imagination, as they apply particularly to this specific technique. There is a fundamental distinction between conscious visualization of an image consciously chosen and the imaginative function which is spontaneous, creative and mostly operates in and on unconscious levels and then offers to consciousness the product or the result of its activity.
In the first case, we can consciously, deliberately evoke an image or set of images of what we have already seen; that is, strictly speaking, reproductive imagination. We can also consciously evoke an image of something we have never seen, i.e., build up an image which may include elements already seen but combined in a new way, which in this sense is a creation of a certain kind. But in these kinds of evocative imagination, it is a conscious creation of a static image. Therefore, it is a creation of quite a different kind from the spontaneous creative function which we will take up later.
The real difference is that in evocative imagination it is a conscious process, deliberately carried through, while the other is the spontaneous function of creative imagination, although the starting point—as we will mention later —may be the conscious evocation of a symbol. It may be interesting to add at this point that—curiously, in a certain sense—it is much easier to evoke even a complex picture or image of something we have seen repeatedly (e.g., the front of a cathedral with its complicated details) than to create a new image, however simple. (From Psychosynthesis, p. 145, 1965)