If that boundary is a wall, you are a captive. If that boundary is a chain, you are a prisoner. If that boundary is a single point of attachment , you are something stranger: a , a living compass whose needle always points toward the thing you cannot touch.
The door is right there. The bar is only metal. And yet. One Bar Prison
You are not sure you aren't already inside one. If that boundary is a wall, you are a captive