what is chapter 13 all about?

Black Beauty narrates another story of mistreatment in Chapter 13. In this case, a young boy is attempting to drive his pony to jump over a high gate. When the pony refuses to jump he starts thrashing the poor thing, driving it to such a point that it throws him off. John—as a witness to this—tells the boy he got what was coming to him and then makes sure the boy’s father knows that he was abusing his pony. Later on John mentioned the incident to James, who confirmed that the boy was indeed a bully, known for his habit of torturing little bugs. James recounts one incident when the boy was taking flies and pulling their wings off. When the teacher found out he punished the boy severely and warned the students against cruelty, labeling it as “the devil’s trade-mark.” Anyone who loved cruelty belonged to the devil. Upon hearing this, John reaffirms the teachers message, advising James that religion is in large part to love and be kind to man and beast and if it does not contain those then it is a sham.