In Joseph Conrad's "Heart of Darkness," the protagonist reflects on a conversation with an old doctor who believes that tracking mental changes in people could be valuable for scientific research. This idea resonates with the protagonist, who begins to see himself as a subject of interest for science, as he undergoes profound psychological transformations throughout his journey.

The notion of becoming "scientifically interesting" suggests a detachment from his humanity, highlighting the impact of his experiences in the dark heart of the Congo. This shift in perspective raises questions about identity and the effects of environment on the human psyche, making the protagonist's struggles symbolic of broader themes within the narrative.