What does Matthew 13:15 mean?

Their hearts have grown numb. They barely hear with their ears, and they’ve shut their eyes. If they’d open up, really listen and see, they’d turn back to me and I’d heal them. Matthew 13:15 - Modern Text Bible

(This verse explains why people don’t respond: they’ve closed themselves off. God wants to heal them, but they have to be willing to see and hear first.)