The human animal
The conception of human being as animal is both literal and symbolic. It is literal because it is quite literally true. Human beings are animals that are born and that die and that reproduce sexually. They belong to the same category of animal as apes. Yet, it is also symbolic to remember this aspect of human reality, because it signifies a return to the literal truth of reality from the daily subjective consciousness of life. Instead of seeing what differentiates humans from animals, this book remembers that at all times, humans are animals behaving out of instincts.
Jesus as the animal god
With this remembrance in mind, that humans are animals, Chesterton invokes the symbolism of Jesus Christ's divinity. The Christian myth maintains that Jesus is the creator God incarnate. He is both the creator of the universe and a character within his own created universe. The interpretations of this symbol run the gamut from dogmatic to mystical, but in Chesterton's treatment, the symbol is absolutely mystical. He sees Jesus as simultaneously the creator God and as an evolved animal. This symbol has transcendental implications.
Divine essentialism
The book's central argument can be seen as an interpretation of life as an allegory with meaning. By adding back into the equation that technically, humans are animals with unique attributes, Chesterton attempts to re-frame humans philosophically as animals with an obviously divine essence. The human essence would be the quest to capture life's meaning through language and art, says Chesterton. This means that human art is a symbolic reminder of their divine essence.
Cave drawings
For Chesterton, the idea that humans are divine animals extends back as far as humans were able to see their lives as inherently meaningful and to capture that meaning through some sort of art. This goes back at least as far as the first recorded artwork, the cave drawings in France. These ancient caves depict humans in their quest of survival, cooperating and attempting to orient themselves to the natural forces. There are literally depictions of animal gods in those cave drawings, so the symbol is quite apt.
Darwinism and interpretation
The book is essentially a counter-argument to the atheist interpretations of Darwin. Chesterton argues that one can interpret the facts of evolution within the realm of theism as well as atheism. This makes scientific fact into a symbol of truth instead of truth itself, because the facts are being interpreted. Chesterton says that because the ideas of evolution and survival of the fitness are commonly understood as proof against the belief in God, that is sometimes taken for granted, but one can obviously believe that evolution is itself divinely ordained.
