The religious fact seems to be universal and goes back very far in human history. It is supposed that its existence is based on the exceptional properties of the human brain, which by the number of neurons and their relations is out of the range of all primates. The constant activity of the nervous circuits creates in a being endowed with the consciousness of his own existence the feeling that a part of his life escapes him, that which he perceives and memorizes in the dream. The need to maintain control has pushed the human being to seek a "rationality" in the existence of supernatural forces. Artistic creation also responds in parallel to this attempt at mastery. The discovery that certain substances operate at will the entry in the states of the dream played an important role in the constitution of rituals making pass this feeling to the level of the group. An increase in the complexity of interpersonal relations in the first societies led to the association between rituals and power, until the appearance of institutional religions in the "historical" societies. We are far from having surpassed a stage that constantly endangers humanity.