Edges are a risky business. And maybe it’s only the association of discomfort I remember from standing on the edge of a cliff, have with sensing the degree of sharpness of a cutting blade or remembering the tension of something being likely to start.
Boundaries on the other hand seem to be there to contain things. Whatever is inside is there to stay inside. Whatever is outside would then stay outside.
Frontiers on the other hand are there to be permeable. They are there to regulate the flow from one side to the other. Frontiers are an important factor in creating homeostasis and thus enabling the system to support its existence.
All three describe limitations.
The way people approach limitations depends on how they perceive them and what they use them for.
Crossing a frontier serves a purpose. Approaching an edge invites courage. Boundaries can be expanded.