Knowledge concerns itself with what is present to the senses, but is also a stored and shared repository of publicly acceptable thoughts, many frozen into physical symbols (written or spoken), transmitted through time and space. Knowledge coded, stored and expressed using symbols can, because of the entrancing flexibility of symbol systems, be broken up and reassembled in a multitude of novel combinations. It is this act of recombination which underlies the power to imagine. Our imagination is and must be grounded in our knowledge. The more memories we accumulate, the more material we have to work with, the richer and stranger are the fruits of our imagination.
Imagination, however, is not just the recombination of stored experiences. Such recombination happens every night even in organisms blessed with much less cortex than human beings. What distinguishes us is our capacity for controlled and wakeful dreaming. This is a useful survival aid, helping us to solve problems, anticipate challenges and conceive alternatives. But we have turned imagination into much more – a good in itself. Like money, sex or drugs, we use it to satisfy our needs, flaunt our wealth and status, tighten our social bonds, or distract us from realities we would rather avoid.