Religion is a collection of cultural systems, beliefs, and world views that establishes symbols that relate humanity to spirituality and, sometimes to moral values. While religion is hard to define, one standard model of religion, used in religious studies courses, was proposed by Clifford Geertz, who simply called it a "cultural system." A critique of Geertz's model by Talal Asad categorized religion as "an anthropological category." Many religions have narratives, symbols, traditions, and sacred histories that are intended to give meaning to life or to explain the origin of life or the universe. They tend to derive morality, ethics, religious laws, or a preferred lifestyle from their ideas about the cosmos and human nature. According to some estimates, there are roughly 4,200 religions in the world.