Anna Sewell repeatedly appeals to her reader's sense of ethos in Black Beauty through her use of a uniquely credible narrator. For example, there are several places where Black Beauty comments on the harsh handling of horses by ignorant humans. Describing his feelings about the harshness of the bits his drivers use, he says:
Our mouths are so tender, that where they have not been spoiled or hardened with bad or ignorant treatment, they feel the slightest movement of the driver's hand, and we know in an instant what is required of us.
When an author appeals to an audience’s sense of ethos, they are making a case for the reliability and credibility of their work. After all, who better to tell a horse’s tale than a horse? As an instructional novel advocating for kindness towards horses, the book’s use of a first-person narrator lends credibility to Black Beauty’s experiences. Through his perspective, the story gains authenticity and moral authority. In this passage, the narrator explains why it is not necessary to use sharp bits or lots of force to direct horses. He also implies that doing so only makes it harder for horses to follow orders. Treating them gently lets them feel the “slightest movement” of the driver’s hand, but mauling their mouths makes them “spoiled or hardened.”
Sewell amplifies this appeal to ethos through many of the anecdotes Black Beauty “tells” his reader. They are invited to see an animal’s perspective on situations where they might not otherwise consider it. Moreover, the author also suggests that not all humans have the same level of understanding, but that it's possible to learn to be better. Even if horses can't share their perspectives in real life, people can educate and encourage one another to treat horses and other animals well.