I read the following story in Adam Phillips's Darwin's Worms:
John Cage tells the story somewhere of going to a concert of music composed by a friend of his. The composer had also written the programme notes for the music in which he said, among other things, that he hoped his music might go some way to diminishing the suffering in the world. After the concert his friend asked him what he thought of the event and Cage answered, "I love the music but I hated the programme notes." "But don't you think there's too much suffering in the world?" the friend asked, obviously put out. "No," Cage replied, "I think there's just the right amount."
Perhaps Cage really thought there is just the right amount of suffering in the world; perhaps he was one of those who think the amount of suffering in the world is just the amount that God allows. But suppose he did not think that. In that case he did not literally mean what he said, but he sill managed to express what he wanted to express. And it is this reading of what he said that makes the story interesting.
So what did Cage express? Well, we can understand what he expressed differently. I think what he meant to express was that it is not the job of music to diminish the suffering in the world. However, if he had said, "It's not the job of music to diminish the suffering in the world,", he would not have expressed what he wanted to express in the way he wanted to express it, and the effect of his words would have been different.