Dramatic irony is everywhere in Black Beauty. The author uses it to underscore the novel’s theme of misjudgment of animals by humans. Horses are thinking, feeling beings just as people are in this novel's world. The irony is ever-present because Black Beauty—though unable to communicate in human language—understands the conversations and actions of humans around him perfectly.
One notable instance of dramatic irony occurs when Black Beauty becomes aware that the groom Filcher is stealing his oats. Filcher makes a blanket statement criticizing horses, to which Black Beauty responds tartly:
‘Dumb beasts!’
Yes, we are, but if I could have spoken, I could have told my master where his oats went to.
The irony of Filcher's name becomes clear, here, as “filching” is another word for pilfering or thieving. Even though it’s clear to the reader that it’s him who is committing the crime, the other humans remain oblivious to his deceit. The narrator knows exactly what’s happening, but he’s rendered powerless in the face of this human trickery and his own lack of speech.
The term "dumb" in this context refers to the inability to speak. Because Black Beauty can’t speak human language, he is unable to convey what he knows about Filcher to his master. The people around Black Beauty mistakenly presume that he can't understand or grasp their actions and words. This recurring motif challenges the readers' preconceptions about horses' intelligence, pushing them to reflect on the possibility that animals have unrecognized or under-appreciated thoughts and feelings. Sewell paints a vivid portrait of animals' depth, awareness, and emotional complexity in these moments of dramatic irony.