Alan Kay coined the term "blue plane". To explain it, he needed to tell a story.
A story of the Grand Canyon.
A canyon that was slowly created by the Colorado River. Etching deeper and deeper, into the earth. Until it created a world unto its own.
If you have ever been to the bottom of the canyon you will understand. The journey down is a long one. As you descend, you notice that the world above drifts away. You enter another world. The world of the canyon. It is a profound experience.
There, at the bottom, is a new reality. You also notice that the light down there is different. It has a pink hue, as the sunlight reflects off of the canyon walls.
There, you soon make decisions entirely from the context of this reality. What is possible. What is not possible in this horizontal pink plane.
Kay talks about our current reality is being similar to this pink plane. The plane in which we make our decisions based on what we believe to be possible.
He then challenges us to look toward the sky above us, to that small, intense sliver of deep blue that is above the canyon walls. Where there are no limitations. Just the infinite blue sky.
If we reimagine the possible based on that perpendicular blue plane, our thinking shifts. We are no longer constricted by the possibilities of the present, but inspired by the potential of an illusory future. As we reimagine on that blue plane we can boldly aspire to an audacious aspiration.
With this audacity, Kay led the reimagining of what a computer is, turning it from a calculating machine to a tool that could unleash our creativity. One that would lay at the foundation of our new economy.
For while at Xerox’s research facility in Palo Alto (PARC) 
in the 1970's, Kay's team was not simply building a user interface for Xerox's Alto computer, but a radical new user experience for an imagined Dynabook , a simple hand-held graphical computer that a child might use in a distant future that served as an Imago Image to defined their creative intention.
An experience that was introduced to the general market by Apple in 1984 with the Macintosh computer. A computer that changed everything.
Kay's concept of the blue plane that transforms our creative potential was inspired by _The Act of Creation_, a 1964 book by Arthur Koestler .
In this book, Koestler developed a theory that creativity is derived from the juxtaposition of two orthogonal planes, what he called matrices of thought. These two matrices form a "bisociation" that forces an assimilation that leads to the development of new framework of understanding.
A "bisociation" that creates the potential for Trialectical Synthesis.
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