outpost of progress

One of the most prominent themes of the story is the gradual moral regression of Europeans in a savage setting in the tropics, a characteristic subject of Conrad's early and middle fiction. Kayerts and Carlier begin their few months at the isolated interior station with optimism, lacking awareness of the psychological perils of the boredom and sense of insignificance that await them during their months at the station.

Conrad also notes the limited nature of the two agents' imaginations. Had they been more imaginative, they might have understood better the peril they were entering. However, the story depicts Kayerts and Carlier turning to reading for entertainment for the first time, and becoming fascinated with the romantic exploits of heroes like D'Artagnan in Alexander Dumas' novels and Hawkeye in James Fenimore Cooper's Leatherstocking saga. The presence of such books turns out to be ironic: Conrad implies that such heroic models will not be helpful in the reality of the African bush.