The Heart of the Matter shows many aspects of twentieth-century atmosphere and ideology as well as modernism and realism.

The novel is set in the midst of World War II, one of the defining events of the twentieth century, and it showcases all of the fear and intrigue of wartime. In fact, the protagonist, Major Scobie, finds himself in the center of smuggling and spying, and he gets in far over his head because of his own greed.

As for ideology, we might turn to the crisis of faith that Scobie experiences. He is Catholic, and he believes in the teachings of the church. Yet he does not follow them, especially when he gets involved with Yusef and commits adultery with Mrs. Rolt. Scobie ends up falling into despair and committing suicide.

In terms of modernism, we can identify individualism at the heart of the novel. Major and Mrs. Scobie are both focused on themselves, for one thing, rather than on their relationship or on other people. Further, the novel centers around Scobie as a character and on the absurdity of his life and situation (another element of modernism).

Finally, the novel is certainly realistic. It focuses on Scobie's everyday experiences, the ins and outs of his life as a chief of police, his failed ambitions, and his broken relationships. Nothing in the novel is idealized. Rather, the characters are presented in all their mundane detail.