Black Beauty’s mood is complex and variable. As the horse grows and changes over the course of the novel, the novel's mood shifts with his circumstances and developing personality.
In the story's initial chapters, there's an overarching sense of hope and understanding. The narrator is born into a welcoming and pleasant environment where he’s well cared for. Even when Black Beauty undergoes "breaking"—a common practice of taming and training horses—it's not depicted as a grievous event. Instead, it's presented as a routine phase in a horse's life, despite its unpleasant name. This early optimism establishes a bond between readers and Black Beauty, making them invested in his future. The mood is bright and cheerful.
However, this comforting mood gradually evolves into something more nuanced. By midway through the book, a more somber mood takes hold. Black Beauty’s anecdotes about his many owners and many jobs shed light on the frequent hardships and overt cruelty horses faced. Sewell unflinchingly delves into the grim realities many horses endured in the Victorian period. The narrative mood becomes increasingly serious, impressing upon readers the seriousness of the broader issues at play.
This gravity deepens as the tale unfolds. The once hopeful and vibrant Black Beauty appears increasingly dispirited, a direct result of the relentless hardships he faces. The novel has a happy ending, however. Towards the end, the narrative mood brightens significantly. As Black Beauty reunites with an old owner and goes back to being cared for in a nurturing environment, the novel reverts to its early optimism. Its mood demonstrates its message: that life goes better if people are kind to each other (and to horses).