I like this quote from Freund describing fantasy, and am quoting it from the book:
The creating of the mental domain of phantasy has a complete counterpart in the establishment of "reservations" and "nature-parks" in places where the inroads of agriculture, traffic, or industry threaten to change ... the earth rapidly into something unrecognizable. The "reservation" is to maintain the old condition of things which has been regretfully sacrificed to necessity everywhere else; there everything may grow and spread as it pleases, including what is useless and even what is harmful. The mental realm of phantasy is also such a reservation reclaimed from the encroaches of the reality principle.