Darkness and Light
Most often, darkness symbolizes ideas such as evil, madness, and depravity, while light represents hope and purity. In both novels, darkness overshadows and even perverts light.
In Heart of Darkness, Marlow travels into the darkest,uncharted corner of the world and discovers that the force that was touted to bring enlightenment, namely the Europeans, have instead created a horror that is beyond words. In his pursuit of ivory (something that is physically light), the white man has embraced and encouraged the darkest parts of his nature. Rather than enlightenment, what has been fostered is murder, madness, death, and destruction.
The Great Gatsby’s symbol of light is the physical light that stands on the end of the dock. It represents all that Gatsby has yearned for: his desire to achieve the American dream, and his love for Daisy. However, by the end of the novel, both of these pursuits have become tainted and have crumbled and decayed. In this decay, they resemble the darkness and desolation of the Valley of Ashes, a place of moral and social devastation.