This study demonstrates the impacts of monism and pluralism on the legal development of a nation. First of all, this study discusses how isms or sects or ideologies begin, related to supernatural thoughts by humans. Subsequently, these thoughts develop into a concept that nature is the center of this universe. Nature sign is not due to supernatural power or in other words rain falls not because the Rainy Goddess is crying but nature itself moves its power. Nature supreme grows well in human knowledge, through natural studies, which is called naturalism. Naturalism continuously forms materialism, something that presents/exists, and then it is what is called the truth. Next, these thoughts develop to mechanistic and vitality thoughts. These give impacts to culture, social even legal system in a nation.