Active imagination is a conscious method of experimentation. It employs creative imagination as an organ for “perceiving outside your own mental boxes.”
For the first hundred years of active imagination, it was applied primarily by individuals for exploring their own sub- and unconscious; hence its value in psycho-therapeutic settings.
Until the theme of the “inner child” in the 1970s, active imagination was most closely associated with C. G. Jung’s experiments with himself and with clients emphasising its therapeutic value.
Beginning in the 1980s, active imagination found uses in commercial disciplines; for example, architecture and molecular biology (how do those complex molecules fit together?).
Where active imagination seeks to perceive what is already present, fantasy intends to create where nothing yet exists.
Source: https://en.wikipedia.org/wiki/