Once upon a time my view of flies was centered on trying to duplicate the object I was trying to imitate. I did this for many years and tied many flies that caught fish well, then one day something in my way of looking at nature changed and I began to see flies differently. I experienced a shift in my perception, a paradigm shift and no longer viewed flies as objects that should look exactly like replicas of what I was trying to imitate. I realized that to fish, flies are perceived as living beings and even if they are perfect replicas to the human eye they may not catch fish because a fish. A fish responds to the illusion of life, not exact physical likeness.
Source: Ken Abrames – A Perfect Fish.