William Golding's "Lord of the Flies" is highly symbolic. Each of the major characters - Ralph, Jack, Piggy, and Simon - stands for various characteristics of the human being.
Ralph is a natural leader, but only because of his appearance, his good looks, his athletic body, and his apparent calmness. However, the true test of a leader is whether or not others will follow him. The boys on the island soon fell away from Ralph's influence because he was "too serious." He wanted them to always work; i.e., building shelters, keeping the signal fire going, etc. He needed to "chill out" and let them be little boys once in a while, having some fun.
Jack, Ralph's nemesis, is more clever than Ralph, and he knows what the boys want. "I got you meat!" He is the hunter, the provider, and he fulfills the boys' immediate needs. He fills their stomachs! Ralph only offers them the intangible "hope of rescue." In other words, Ralph offers them a possible future, while Jack gives them a definite "now." It reminds me that most drug dealers, actors, athletes, and prostitutes all make better salaries than most teachers, priests or philosophers for the same reason.
Piggy is the brains behind Ralph, but Piggy (as his name implies) is fat, making him an outcast. He has glasses, asthma, is lazy, whines, and is, in essence, the stereotype of a nerd. He has great ideas, but the boys can't see past his shortcomings to grasp the wisdom of what he has to say. He is, in many ways, more of a threat to Jack than Ralph is because of his intelligence.
Simon is the most complicated character on the island. He is shy, younger than the other three mentioned, calm, a little aloof, and very kind. He is constantly thinking of others - feeding the little'uns (little ones), continually working on building the shelters, trying to convince the others that "the Beast" is not "out there" but is within themselves, and frequently venturing off alone into the forest to "think." He is the one who finally encounters the evil on the island (in the form of the Pig's Head) and later discovers that "the Beast" is not someone or something to fear but simply a parachutist caught in a tree at the top of the island. When he descends the mountain to free the boys from their fear of "the Beast," they mistake him for that very "Beast" and kill him.
Ralph and Jack both represent leadership, Ralph's being a form of democracy and Jack's being a dictatorship. I think they both also represent "the body." Piggy definitely represents "the mind," and Simon is "the soul." Unfortunately, Ralph (the good leader) needs a Piggy giving him solid ideas and a Simon giving him a spirit to be successful. Jack, on the other hand, manages to eliminate both Piggy and Simon, and he would have killed Ralph if the boys had not been "rescued" by a Navy ship at the very end of the book. Ironically, they are "rescued" by a group who are playing the same dangerous "game" the boys were playing on the island, but their game is involvement in a world war.
Golding's message is, I feel, quite pessimistic; however, I feel that as long as there are Piggys, Simons, and Ralphs in the world, there is a chance to counterbalance the Jacks and make "this island" a happy and wonderful place to live.