Simon's death is one of the greatest tragedies in William Golding's Lord of the Flies, both because of who he is and how he dies. Simon is the character who is most sensitive and represents the best part of human nature. He is the only boy who recognizes the true beast on the island--it is them. When he frees the parachutist, the beast from the air, he is demonstrating a compassion which he is not given. In these final paragraphs, it seems that Golding is mourning the loss of civilized behavior.
When Simon meets the Lord of the Flies, he is forced to recognize the reality that it is the nature of man which is causing such savagery on the island; when he tries to tell the others about his discovery, they kill him. It is true that they did not quite realize what they were doing in the midst of a dark, stormy night and in the middle of a chanting, frenzied circle; nevertheless, the boys did kill the lone voice of truth.
Because truth and goodness are now gone, Golding chooses to mourn that loss in the last four paragraphs of chapter nine. As the answer above suggests, the connection of Simon to nature is clear, as is the Christ imagery.
Nature provides him with a natural halo:
The water rose farther and dressed Simon’s coarse hair with brightness. The line of his cheek silvered and the turn of his shoulder became sculptured marble. The strange attendant creatures, with their ﬁery eyes and trailing vapors, busied themselves round his head.
Golding stops short of depicting Simon with his arms spread out like Christ on the cross; however, the image is not hard to imagine as his body floats lifelessly out to sea.
The great wave of the tide moved farther along the island and the water lifted. Softly, surrounded by a fringe of inquisitive bright creatures, itself a silver shape beneath the steadfast constellations, Simon’s dead body moved out toward the open sea.
As Simon's body floats away, so does the best part of human nature (symbolically). What happens after this is a quick descent into savagery, for there are no elements of nobility left to stop it.
Golding uses imageries of nature to show how Simon was connected to the natural world. After Simon's death, a sense of serenity takes over the beach and even the sea seems to become less agitated as “the rain ceased, and clouds drifted away". Although Simon’s death was sad, gruesome and untimely, Golding tells us that “creatures with fiery eyes” surround Simon’s body and turn him into a beautiful figure of “sculptured marble”. “Everything was coated with a layer of silver”, which softened the enormity of Simon’s death. Golding uses bright colors and descriptions such as “phosphorescence” which implies that although Simon is dead, he is “brought back to life” by the nature all around him. The images created by the sea and the cosmos, makes Simon’s exit aesthetically appealing to the reader. The sea is beautifully described as something that accepts the body of a martyr (Simon), to enclose, protect and remove it from the evil of the island. Simon’s exit was “beneath the steadfast constellations”. Due to his relationship with the cosmic world, Simon is differentiated from the other characters by his innocence and his relationship with the natural world. Therefore, the mood created in these paragraphs is scenic yet touching to the reader.
During the four paragraphs that Golding uses to describe Simon’s journey out to sea, he draws more parallels to Simon being a Christ-like figure; Golding is resurrecting Simon. Slowly, Simon becomes human again as "the beast lay huddled on the pale beach". The calm sea appears to be soothing Simon, as it takes him on his last path, to the bottom of the ocean. The glowing fish in the ocean function as a kind of “living halo”. They do not eat the body but perhaps they are figuratively honoring the body. Movement in the water, made by the tiny creatures, could also suggest a transcendence of death. The use of light and dark colors, contribute to create a feeling of infinity in the passage. For example “the water rose further and dressed Simon’s coarse hair with brightness”. These lights that are around Simon are a symbol of him rising up to heaven.