What is meant by “secret society”? Is it simply a secret association, i.e. a social group concealing its existence, its meeting places and / or the name of its members? It is in fact more than this simplistic definition: the clandestinity – in the anthropological sense -whether absolute or relative, is not enough to define a secret society, because this hidden, isolated character, outside the profane world, is generally forced because of opposition from the authorities in place. So, what is the link between the Carbonari of Italy (19th century), the Bizango of Haitian voodoo, the European Freemasons, the mafia of Cosa Nostra, the Hells Angels or the MS-13 of the United States, and the Zangbeto of the Beninese voodoo?

What makes the society secret is, first and foremost, the sharing of specific secrets reserved in principle for its members alone, but also the sharing of special rites that aggregate the members. So they have both secrets and rites in common. But these secrets are not easily revealed, it must first undergo tests (sometimes truly physical, sometimes symbolic, often mixed). These trials constitute initiatory rituals, a new entity shared by the affiliates: thus did the Freemasons all “see the light”, thus the aspirants are all “dead of their former life”, thus the MS- 13 were beaten for 13 seconds (or gang-raped for one minute, for girls), etc. This unifying experience that makes these members true siblings  are sometimes purely initiatory (at the center of which is a religious, magical or metaphysical esotericism) or sometimes secular (political, social, criminal). Other more secret secret practices follow means of recognition between initiates, oral or written traditions (concerning the aims and origin of the group).