He conducted field research for three years while living with the Lacandón Indians in Chiapas, Mexico investigating shamanism first-hand, and completed his doctorate on their incantations and spells.
The earliest known written magical incantations come from ancient Mesopotamia (modern Iraq), where they have been found inscribed on various cuneiform clay tablets excavated by archaeologists from the city of Uruk and dated to between the 5th and 4th centuries BCE.
Several linguists and anthropologists have done extensive studies of Lacandon language and culture, including Phillip Baer, a missionary linguist with Summer Institute of Linguistics who lived among the Lacandon for more than 50 years, Roberto Bruce an American linguist who devoted his life to studying Lacandon language and culture, and Christian Rätsch who spent three years living with the Lacandon while studying their spells and incantations.
...and I read, too, of the lost, grim black cavern high in the hills where the horrified Turks hemmed a monstrous, bloated, wallowing toad-like being and slew it with flame and ancient steel blessed in old times by Muhammad, and with incantations that were old when Arabia was young.