Entry into the priesthood of a vodun runs through a period of seclusion. Initiates enter a convent community under senior priests, are taught the songs, salutations and obligations of the deity they will serve, and emerge with a new name and a changed standing. The duration, the content and the ordeal vary by deity and by house, and none of it is public. The atlas records that this is how the tradition transmits itself, and does not set out what is taught, because the material is closed and printing it would not make it open, only stolen.
Fa is the divination system that regulates the rest. A diviner casts and reads one of a fixed set of signs, each attached to a body of memorised verses, and the sign indicates what is owed, to whom, and what must be done. It is the mechanism by which a person learns which vodun has a claim on them, and it is closely related to the Yoruba system of Ifa across the border.
Public life is a different matter and is genuinely public. Festivals bring masks, drumming and processions into the open, the ceremonies at Ouidah draw visitors from the diaspora, and Benin marks a national vodun holiday each January in which the state itself takes part. Anyone may attend.
That distinction, an open festival and a closed initiation, is not a compromise or a concession to outsiders. It is how the tradition has always been arranged, and it is the shape a reader should carry away: vodun is visible, and vodun is not therefore available.