The preface of the book of Isaiah covers chapters 1 through to the end of 5. The prophet sets out to diagnose Israel's condition and offer a prognosis. Up to chapter 5, the infection of sin in the nation's life is not terminal. A remnant exists where there remains the hope of cleansing and a new creation. Yet now in chapter 5 all hope is abandoned.
Nothing is left but doom.
The prophet sings a song about his friend and the vineyard that he planted, v1-2. The prophet sings a love song for his friend, a song whose words become the words of the friend. The friend is described as lavishing the utmost care on the vineyard. The poor results cannot be the fault of the owner of the vineyard. The problem lies elsewhere.