The poem dramatizes a paranoiac fear of some aspects of nature—that is, the fear of being deceived or losing control. In the speaker’s eyes, the very body of the snake is constructed to move in a way that instills fear and uncertainty: The snake is undetectable until the very last moment, just prior to a surprise encounter. The speaker’s rationalist side copes with this fear by enlisting the ideals of 19th century scientific observation, collecting data about snake behavior, diurnality, appearance, and habitats. His literary side attempts to bridge the divide between animal and human, painting the snake as a rider and someone adept with combs—similes that try to make its movements closer to those of people. However, the speaker cannot ever fully be at ease when encountering a snake. Instead, seeing one unleashes unfounded, involuntary terror, which makes it clear that he can never dissociate this animal from its biblical cognate, the serpent from the Garden of Eden, who tempted Eve and Adam to taste the fruit from the Tree of Knowledge of Good and Evil—an action that forced God to expel them from paradise.

The poem thus contains anxiety about the ability to subjugate nature by valuing humanity over the non-human—an idea that undergirded the history of the US.