Fetichism in West Africa: Forty Years' Observation of Native Customs and Superstitions by Reverend Robert Hamill Nassau, a missionary, was published in 1904. This influential work stands as one of the earliest examinations of traditional beliefs in West Africa. Nassau's book delves into his extensive observations over numerous years, detailing the practices of traditional religions and sorcery within West Africa, shedding light on their integral role in the daily lives of the region's inhabitants. John Cinnamon noted that Nassau's insights, free from continual comparisons between Christian beliefs and African practices, offered valuable ethnographic glimpses. Among Nassau's key sources was Anyentyuwe, an influential Mpongwe woman and educator at Gabon's Baraka Mission, whose contributions were pivotal to the book.
