In seventeenth-century Europe the Copts, or the Egyptian members of the Church of Alexandria, were widely believed to hold the key to an ancient wisdom and an ancient theology. Their language was thought to lead to the deciphering of the hieroglyphs and their Church to retain traces of early Christian practices as well as early Egyptian customs. This book, the first full-length study of the subject, discusses the attempts of Catholic missionaries to force the Church of Alexandria into union with the Church of Rome and the slow accumulation of knowledge of Coptic beliefs, undertaken by Catholics and Protestants. It ends with a survey of the study of the Coptic language in the West and of the uses to which it was put by Biblical scholars, antiquarians, theologians and Egyptologists.