The two lines that provide symbolism of death being near are: There was light and now there is darkness and staring with wide-open eyes into the darkness.
Symbolism works because it is supposed to be unsaid, yet implied through the comparison of things with other things. Sometimes and more commonly done with colors. Because symbolism means things need to be unsaid, every line where the narrator mentions dying and death is not applicable here. The last line is also not applicable because it is simply speaking about how the narrator is very angry about it all, and it does not imply that death is approaching. The whole chill coming over him and breath ceasing bit is close, but also not applicable because this implies death has happened, not that it is nearing.
The reason the two lines about darkness are so symbolic is mainly because darkness is symbolic. Blacks and the dark are often symbolic of an end, misery, or death. The fact that the narrator claims there was once light, but now there is darkness symbolizes the fact that there was once life, but now there is an approaching death. The other sentence is also symbolic because although it is more commonly considered "seeing the light at the end of the tunnel," the way the narrator phrases it is similar. Staring with wide opened eyes into the darkness is as if darkness is coming towards the narrator too fast and that he is in shock. This could also mean that death is approaching him at a quicker pace than he would have expected. Darkness can also imply an unbiased view of if there is an afterlife or not.
