A horse misused upon the road
Calls to heaven for human blood.
Each outcry of the hunted hare
A fibre from the brain does tear.
I think this means that every person that gets mistreated wants to seek revenge and every time someone crys out because of something you did it will stay in your mind forever.Also he uses symbols. I think horse means person and road means life. Human blood means revenge.Outcry is emotion and hunted hare is the person being bullied. The last line I am not sure.
One literary device he uses is ambiguuty because that stanza is vague and there are many interprotations that can come out of that.