In "The Island of Doctor Moreau," H.G. Wells explores themes of humanity and the inherent duality within people. The narrator observes moments of darkness when individuals seem to lack their humanity, drawing parallels between them and beasts. This observation highlights the struggle between civilized behavior and primal instincts, suggesting that everyone has the potential for both aspects.

The quote signifies a keen awareness of moral ambiguity in humanity, as the narrator grapples with the idea that people are a blend of animalistic traits and higher ideals. These fluctuations in their nature can overshadow their humanity, leading to a profound sense of instability and conflict within individuals. This duality raises questions about the essence of humanity itself and the societal factors that influence these traits.