Themes are the fundamental and often universal ideas explored in a literary work.

The Reflection of God in People and Nature 

God is an especially powerful presence for Cabot in the play. He continually talks about and prays to God, and religion is a large part of his life and belief system. His motivations are often driven by his belief that he is obeying the will of God. He believes that life is hard and lonely because God is as well, a perspective that is responsible for much of his unhappiness. He also believes in an afterlife, represented by a "wa’m field" in the sky, and it's there that he hopes to find peace. In contrast, his sons do not take God or religion seriously most of the time. Cabot criticizes them for many things, including being sinful. He accuses Simeon and Peter of wanting "sinful, easy gold," and he calls on God to smite them. He also says of Eben that "he's a sinner-nateral-born.” However, Eben does acknowledge the idea of sin, calls out to God on many occasions, and is morally conflicted about sinning with Abbie. It seems as though the idea of God is something that is deeply embedded within the society in which the characters live.  

The natural world is hugely important in the characters’ lives, and the imagery of nature is often combined with the idea of God or religious faith. Cabot’s idea of heaven is a “wa’m field" in the sky, and he refers to his farm as a church that he built on rock. Eben and his brothers are struck by the beauty of the sky at various times, and in the closing moment of the play, Eben and Abbie admire the sunset, in "attitudes strangely aloof and devout" as if they're praying to the beauty of nature.  

The Consequences of Acting on Desire  

As the title suggests, a major theme of the play is desire. This includes lustful and romantic desire, largely illustrated by the relationship between Eben and Abbie. It also refers to other kinds of desire—all the characters yearn for something. This yearning drives Simeon and Peter to go to California. "Somethin'" is also the name that Cabot gives the force he senses in the house. Without knowing about the affair between Abbie and Eben, he still senses their desire for each other.  

The idea of lustful desire and its conflict with religion is illustrated in Eben. Early in the play, he is lusts after Minnie, a girl in town, and he acts on this feeling, though he declares it sinful. Abbie represents sensuality and people’s natural sexual impulses. However, in the process of their relationship, it becomes clear that there is more than lust between Abbie and Eben and that what they both desire is a deeper love. The climactic sin of infanticide comes from Abbie’s desire to be with Eben and to prove her love for him.   

The Power of the Natural World and People’s Natural Impulses 

The natural world is a powerful presence in the play. It is represented in the farm and its animals, the land, the sky, and the trees. The characters are beholden to the natural world in that it's how they earn their living, and they work day in and day out maintaining the land and the animals. Although the characters do not demonstrate joy or love for the land around them, they can’t help but admire the beauty of nature and often speak in metaphors about the natural world. Abbie recognizes nature as a “burnin’ inside ye,” and tells Eben that it will get the best of him. This nature refers to the biological impulse for sex and procreation that seems to drive Eben more than anyone else in his family. The elms of the play seem to represent both the natural world and the natural impulses of people, as they are described in the opening stage directions using words denoting human characteristics, with their peculiar appearance reflecting the emotions expressed in the house.