In a long gestation period, the Dakar-Djibouti mission constitutes the epistemological milestone from which, within anthropology, the science of ethnicity takes shape fortuitously following the study of an unusual social fact: the mask. A radical break with the social philosophy of the Enlightenment? What validity to expect from the observable status of the mental structures of peoples on the margins of History? It is in this glance that the present work (volume 1), is entrusted the task to underline and to appreciate the conflict of the interpretations of the ethnography to the sciences of the language in a heuristic step of the passage of the observation of the object to the description of the concrete sign. To do this, the anthroposemiotic reconstruction of his object was necessary in its double status of ritualized existence and cosmostructured essence: the mask, ontologically ritual, notably among the Bobo'i of Burkina Faso and Mali (West Africa), in this respect, escapes binarisant typologies and questions the tools inherited from semiotics (since Locke.) This reflection postulates that semiotics must necessarily be the sum of altersemiotics