By Jesus' time, Isaiah's vineyard parable had been (deliberately) misread in lots of ways that kept it from serving its purpose as a dire warning to God's people. In Sunday's Gospel, Jesus rescues the allegory from readings that muddled its focus - by retelling it to make its target crystal clear.
People "of a certain age" (the ones that like newspapers a bit too much) would have us believe that cartoons existed before The Far Side and Calvin and Hobbes. One of the ancient cartoons they will tell you about was a political one about a possum (?) who lived in a swamp. And in one story about the causes of pollution, the possum looked at the source of the problem and concluded, "We have met the enemy, and he is us."
The last verse of Sunday's Gospel makes it clear, the people hearing Jesus' retelling of the parable of the vineyard are the ones who need to hear it most (both from Isaiah and from Jesus). They are the ones that God is trying to reach. The people who cannot see that they are the ones that are causing their own separation from God - the ones who need to desperately need to realize that "We have met the enemy, and he is us."
More on this tomorrow.