I Heard an Angel Sing

I have the debate about Singapore politics on Sunday night in mind when I'm reading this poem by William Blake. Sounds like a semi-followup. Read the first 2 stanze and let them impress you before you go on.

I heard an Angel singing
When the day was springing,
"Mercy, Pity, Peace
Is the world's release."

Thus he sung all day
Over the new mown hay,
Till the sun went down
And haycocks looked brown.

I heard a Devil curse
Over the heath and the furze,
"Mercy could be no more,
If there was nobody poor,

And pity no more could be,
If all were as happy as we."
At his curse the sun went down,
And the heavens gave a frown.

Down pour'd the heavy rain
Over the new reap'd grain ...
And Miseries' increase
Is Mercy, Pity, Peace.