Lewis, Ioan M. (1930– ) – Professor emeritus of anthropology at the London School of Economics and author of Ecstatic Religion: A Study of Shamanism and Spirit Possession (1971). His wide-ranging research is important as a clarification of the relationship between trance (an interior state of disassociation) and possession (a culturally mediated interpretation of trance as the intrusion of spirits or otherworld beings), between official and marginal cults (often distinguishable by the gender of the main performers), and between control by and mastery of spirits. Lewis regularly contests Mircea Eliade’s construction of shamanism, generally seeing it as a system imposed on more diverse data. Demonstrating that possession is a performance established and interpreted by particular cultures, he challenges Eliade’s (and Sergei Shirokogoroff’s) assertion that shamans master but are not mastered by spirits. Noticing that practitioners invite possession similarly undermines Eliade’s schema. As such, Lewis broadens the use of the term shamanism beyond the locus classicus of Siberia and the Arctic, specifically to Africa. Lewis’s abiding interest, however, is in the relationship between cults and experiences of possession and the wider social order. Paying attention to details of who gets possessed, what benefit they or others derive from the possession, what social mechanisms contain or are contested by possession cults, what role degrees of social power play in all this, and how shamans and their work fit into clan and other social contexts enables a far richer understanding of the phenomenon than claims about “true” and “degenerate” forms of shamanism. Lewis engages with the Sar, Zar, and Bori cults of East, North, and West Africa, in which women play significant roles despite their general marginality in locally dominant forms of Christianity and Islam.