Flint's main argument is that while some major governments in early medieval Europe, influenced by the example set by the former Roman Empire, tried to suppress the practice of magic, eventually it experienced a revival and came to flourish, encouraged by a new belief that it could be beneficial for humanity.

Divided into four parts, in the book's introductory section, Flint discusses the source material that she is drawing from, and offers an overview of the view of magic that medieval society inherited from both the Classical world and the Judeo-Christian tradition.

These second thoughts led, I shall attempt here to prove, not merely to the halting of the process of rejection and to the tolerance of certain "magical" survivals, but to the active rescue, preservation, and encouragement of very many of these last; and for all the furtherance of the relationship between people and the supernatural that, it was fervently believed, would improve human life."

For the purpose of her study, Flint defines "magic" as "the exercise of preternatural control over nature by human beings, with the assistance of forces more powerful than they."

Flint also highlights the manner in which Judeo-Christian tradition condemned the practice of magic, both in the Bible and in un-canonical literature such as the Book of Enoch, and in particular the laws that were enacted against astrologers by the Roman Senate.