Analysis of poem #23

One of their neighbors is afflicted
With a fell spirit, lost, and doomed
To roam alone among the tombs,
The spirit’s fierce, but some have tricked it.      
Citizens have bound the madman tight,
Caught him in fetters or in chains,
But strength no ligature contains
Breaks them like braided aconite.   
And after this, they let him be
Because his might has always snapped
Twine tying wrists, but flesh has trapped
Unspeakable malignancy.