The moment of insight came to me when I was watching the famous "Matrix Is a System" scene. In this scene Neo pushes himself thorugh a crowd of black & white dressed people, listening intently to Morpheus - only to lose focus when an attractive blonde in red dress passes him by.
I have found that this movie scene beautifully illustrates an important fly fishing problem - one that is especially common during heavy hatches. How should the fly tier / fly fisherman help poor Mr. Trout in choosing one particular individual fly from a swarm of seemingly identical insects?
It is true that the heavy hatches when a layer of mayflies on the water surface resembles a woolen carpet when seen from distance are rare. But still, these are can be surprisingly trying times. The laws of statistics and sheer number of naturals on water ensure that your fly will have to pass a rising fish for many times before getting a strike; all the time risking scaring the fish by badly executed cast and resulting drag.
The contrast of the woman in the red dress vs. black and white crowd illustrates the need to be less imitative in times of fly life overcrowding. Your imitation needs to look familiar in size and shape - the woman in the red dress is clearly human, being neither a midget nor a giant - but has to stand out in the crowd.
The Matrix lady does this by having blond hair and red dress; your fly can get the same result by having a body tied with a gold tinsel instead, or having a bright orange tag, metallic bead head or a contrasting thorax. Anything goes, as long as the difference in color and movement is subtle enough not to scare Mr. Trout / Mr. Neo rather than attract him.