Symbolism, Imagery, Allegory
For Thoreau, animals aren't just woodland buddies, they're also a poetic inspiration, helping him communicate key truths about human nature. Here are some of the most striking animal allegories:
The hound, the bay horse, and a turtle-dove (Economy.23): The story about searching for a lost hound, bay horse, and turtle-dove is in a very crucial spot in the book. Thoreau tells the story while explaining the rationale for his personal quest. This placement may suggest one of two things: either that these animals are metaphors for the elusive (hard to get to) spiritual truth that Thoreau seeks, or that they represent the impossibility of living a fulfilling life when you are caught in the rat race of trying to get ahead in the world.
The striped snake (Economy.59): The spectacle of benumbed snakes makes Thoreau think of how the mass of men live, largely unconscious and oblivious (unaware of the world around them).
The fighting ants (Brute Neighbors.12-13): Thoreau gives us an epic battle of ant versus ant. It's an ugly fight, with each ant becoming dismembered in the process. This gruesome, but really memorable, image leads Thoreau to consider the futility of human war.
The crafty loon (Brute Neighbors.17): Thoreau describes a game of chase he plays with a loon on Walden Pond. The loon is constantly ducking away, then popping up a good distance from him. Like the hound, bay horse, and turtle-dove, the crafty loon seems to be an allegory for Thoreau's spiritual quest – or spiritual chase, perhaps.
The bug in the table (Conclusion.19): This allegory appears in the second-to-last paragraph of Thoreau's book, in a chapter that is geared toward explaining to his readers how his private experiment is relevant to their lives. The bug allegory suggests that we, too, might one day be surprised to discover the same individualized, personal truth that Thoreau discovered on Walden Pond. Wouldn't that be something?