There are many references to animals throughout this novel. The most striking one, perhaps, is the crippled dog that the priest discovers at the abandoned estate. In that scene the priest battles the dog over a bone with a few bites of meat on it and the implicit question is whether anything separates us from the animals. Are human beings reducible to the will to survive? It is a question of great importance to the priest, who often is at a loss to justify his desire to live (especially when he considers the pain his presence inflicts upon others). His struggle with the maimed mongrel over a morsel of meat is a pathetic scene, one in which hunger and the will to live seem to win out over human dignity, and the priest recognizes this. There are also many mentions of insects throughout the novel, notably in scenes involving the lieutenant. Greene refers to insects hurling themselves into lamps or being crushed underfoot. Pointless life careening to pointless death seems to be the import of these details, and the implicit question is whether human life is similarly futile and meaningless.
A striking thing about this novel is the prevalence of "half-things": the mestizo is a "half-caste"; the priest despairs most often over the "half-hearted"; Padre Jose is half-priest, half-husband; Mr. Tench seems half-alive; there are dozens of examples throughout the novel. Moreover, we can see by this list alone that half-things more often than not play some detrimental role in this novel. The priest and the lieutenant are by and large, exceptions—people who refuse half-measures and instead tend towards extremes. Near the end of the novel, the mestizo exclaims to the priest, "you do nothing in moderation." Although the extremities are often dangerous—particularly in the case of the lieutenant's actions—Greene seems to suggest that it is better to live life with intensity and passionate commitment than it is to live in an indifferent or complacent fashion.
Many things are abandoned in this novel, and the words "abandoned" or "abandonment" crop up repeatedly. Many of the townspeople feel that the clergy has abandoned them, and the priest, in turn, feels that the people have abandoned him. Mr. Tench has abandoned his family, Captain Fellows and Mrs. Fellows abandon their house and their dog, and the priest tries to abandon the mestizo on the road to Carmen. These are just a few examples. It is an important motif, because it implicitly raises the most important question, whether human beings have been abandoned by God and left to the cruelty of nature and each other. Significantly, the greatest act of heroism in the novel—the priest's decision to return to help the gringo—is a refusal to abandon someone in need, and a refusal to abandon a dangerous and ugly world.