In my reading, I noticed the descriptions of auditory imagery (or lack there of).  In particular, whenever a situation is frightening Marlow describes the silence.  As I pondered this in my reading, I noticed how silence paralleled to nature, in the fact that they are both uncontrollable. In nature, things are uncontrollable because of all of the different ecosystems, biomes, and constant energy.  With silence, is it uncontrollable because of the lack of sound, or silence taking over as a presence?