A key is an everyday object, but then you hold it up for us, we see light glinting off it, and the suggestive potential of that image is quite enormous. The reader can take that key and go off in a lot of different directions. Also, we're writing in beats, which we can examine our own spoken language for. If you let the colors and the things in your poems have the rhythms that they have, there's an eventual unity that comes out. One's life is laden with messages, but you need to read them.
Poetry is a system for reading.
This poem really collects and organizes a lot of these messages. I can tell you about some of the characters in this poem. As he was dying of brain cancer, his powers would cease one by one. One of the things he became obsessed with was how the bottom of the sea was flooded with light. There were fish with little lights on the tops of their heads, and all forms of phosphorescence, and he was thinking these thoughts as the world around him was growing dark.