I heard an Angel Singing
When the day was springing:
"Mercy, pity, and peace,
Are the world's release."

So he sang all day
Over the new-mown hay,
Till the sun went down,
And the haycocks looked brown.

I heard a devil curse
Over the heath and the furse:
"Mercy vould be no more
If there were nobody poor,
And pity no more could be
If all were happy as ye:
And mutual fear brings peace,
Misery's increase
Are mercy, pity, and peace."

At his curse the sun went down,
And the heavens gave a frown.

William Blake

http://www.poemhunter.com/poem/the-two-songs/