at the frontier of the skin

"At the frontier of the skin no dogs patrol.
At the frontier of the skin
Where I end and you begin
Where I cross from sin to sin
Abandon hope and enter in
And lose my soul.
At the frontier of the skin no guards patrol
At the frontier of the skin mad dogs patrol
At the frontier of the skin
Where they kill to keep you in .
Where you must not slip your skin.
Or change your role.
You can't pass out I can't pass in.
You must end as you begin.
Or lose your soul.
At the frontier of the skin armed guards patrol."