It is not a physical thing, but rather the boundary I have come to recognize, in my mind, my emotions. Its the line in the sand, the point of the hill where you can't climb back up from. And it isn't singular; there are several and each has it's own emotional and physical pains.
The edge I most frequently cross is that of Spiraling; another word I give special connotations to. Years before I knew the terms for any bipolar issues I knew this. When things are decent, my thoughts flow in a line I can follow and not fear, from one topic to the next. And I don't notice that my pattern of thoughts is slipping before it begins.
Frequently my inner