Black Beauty’s health is starting to suffer, and he’s losing trust in the people who care for him. Noting that it’s not normal that he foams allows him to teach readers what a horse should look like as it works—potentially arming readers to say something when they see a horse foaming and uncomfortable, as Joe Green did earlier. Fortunately, Black Beauty implies that his time working with the bearing rein is coming to an end—but that is, of course, no guarantee that whatever comes next will be better.