It is not easy being a prophet when your message is full of judgment. Isaiah, obviously knowing this, presents himself as a minstrel and "...beguiles his unsuspecting audience with a song. It is striking example of just how creative and skillful the prophets could be in communicating their message (gospel preachers take note!)" - Webb, p54.
Webb goes on, "...Isaiah loved the LORD passionately, and it was because of this that he could identify so closely with both the outrage and the grief that the LORD felt at the willful sinfulness of the nation. (We should note this carefully if our religion has become passionless. Our capacity to share God's anger can be an indicator of how much we really love Him.)" - p55.
And so, Isaiah would sing -
Now let me sing to my Well-beloved
A song of my Beloved regarding His vineyard: (Isaiah 5:1a)