What is the purpose of "By the Waters of Babylon?"
The purpose of "By the Waters of Babylon" is to highlight the nature of human ambition and the inevitable conflict it engenders.
In the story, John is taught that he must honor the laws of his tribe. One of the laws states that the Place of the Gods is strictly forbidden to him. Yet, after John makes a first visit to the Dead Places with his father (a priest), he becomes emboldened to explore previously forbidden regions. His resolve is aided by the fact that he was not hurt by the metal his father found in one of the Dead houses.
John's ambitions are also fueled by his pride in his heritage. The text tells us that John is especially proud of the fact that his people are "not ignorant like the Forest People" and that they "do not eat grubs from the trees." His hunger barely satiated by his forays into the Dead Places, John begins to harbor ambitions of seeing the Place of the Gods. His father warns him against his hubris, but John is adamant. He determines that, as the son of a priest and a future priest himself, he will not be intimidated by the unknown. His superstitions may cast doubts in his mind, but they will never stem his resolve.
John's actions are a direct manifestation of his curiosity and his inherent need for meaningful answers to his questions about life. When he finally reaches the Place of the Gods, he discovers that his past superstitions are an inadequate guide in the strange world he has entered.
Our protagonist comes to realize that he has to rely on his instincts to survive. There is no magic that can save him from a pack of feral dogs; to live, he must outrun them and hide. John also ignores his past training to eat what he finds in one of the houses. In this new world, survival is based on instinct, faith, and courage. The rules and superstitions of old cannot aid his understanding of a culture that is foreign to him.
In the end, John experiences an epiphany brought on by a fantastic vision. The Place of the Gods in all its majestic vibrancy is presented to him in a vision. He sees the "gods" as they were and calls what he sees "magic." It is this "magic" that he hopes to learn more about, despite the fact that he now knows that these "gods" were merely men. As the story ends, John's enthusiasm is infectious, but there is also a note of foreboding. John is adamant about rebuilding the Place of the Gods, but we question whether John's naivety will blind him to the ambitions and hubris of past generations who destroyed their world through conflict and war.
"By the Water of Babylon" is a warning against using human knowledge too quickly without thinking of the consequences. At the end of the story, John says that the people in the City of the Gods, "ate knowledge too fast." In other words, they developed weapons and then used those weapons before they fully understood what the consequences for their civilization would be. Many people assume that the author was warning against the atomic bomb. However, the story was published years before the atomic bomb was first detonated, so his warning is probably much broader and includes other weapons of mass destruction such as chemical and biological weapons which did exist at the time he wrote this story. The author may also be warning about an inherent flaw in mankind. When John returns to his people, he vows to learn the knowledge he found in the City of the Gods. He is sure that he can use the knowledge wisely. His father, who is older and wiser cautions against this, but John, in his youthful enthusiasm, plans on ignoring his father's advice and teaching his people the new knowledge. Thus, the cycle of destruction may simply continue.