From Tending the Soul's Garden:
"Edge Effect refers to that which occurs in a system along its edges. The principle recognizes the use of natural patterns as the basis of design. In nature, the creation of greater edge provides us with a greater surface area, therefore giving us greater production, increased positive relationship opportunities, more places for nature to create and work and evolve, and a greater edge between microclimates.
In invisible structures, such as a societal culture, the edges or margins tend to foster a greater creativity. In our personal inner world, the edges are the places of greatest discomfort and often can be that “creative edge” where we experience the most personal growth.
It helps to observe and notice the “edges” both in our community and in our lives and cultivate a deeper awareness of the gifts present in these areas."