It's not a natural thing for someone to have the feeling or urge to kill another human being. It is a very small percentage of people that can relate to guys like the Madman in Maupassant's story. But the question at hand is whether Maupassant's story implicates us all in the natural drive toward evil. Conversely, I do feel that the majority of people have something that drives them to do things which are unmoral in today's society. So I agree that all people have a natural drive toward evil, and the judge-killer is just an exaggerated case, but a symbol of our own being none the less. .
He is a symbol in many ways. It isn't so much the need to kill as I mentioned earlier, because those are the people that have psychological problems and end up in jail. But the issues I"m addressing are the ones we sometimes do without consciously realizing it, such as cursing, or having pre-marital sex. Although most often we realize when we are doing wrong, but time and again we don't think when were acting, such as when you cheat on your husband/wife. It is something that takes over our emotions, and it makes you do things out of your regular norm.
The Madman was a person who was highly admired, as he was also a judge and is the person who is supposed to enforce the law. He has dealt with people of his own kind, and yet he has let himself fall a victim to his inner desire to kill. It is scary the way he progressed from killing little harmless creatures, into killing the little boy who was alone just for the excitement of it. .
Although he is a Madman, he seems to back up everything he says in a way that we don't normally think of it. He doesn't feel that humans have a soul, and It seems he feels we have no purpose on this earth. He says, "A being? What is a being? An animated thing which bears in it the principle of motion, and a will ruling that principle. It clings to nothing, this thing." If everyone in the world felt that way, we would live in a savage society with no care in the world.