Thinking of the power of the saints, let me first recall the final chapter, entitled Potentia, of Peter Brown's magnificent book on the cult of the saints, written in 1981. After reviewing how the praesentia of the saints in their relics allowed the emergence of a new type of episcopal power which claimed to be the visible representative of these invisible patrons, thus providing a redefinition of late Roman patron-client relations and the boundaries of the civic community, Peter Brown concludes with observations on the nature of the power of the saints. The quintessence of this power, he states, is to be found in the ‘noisy and frightening experience of healing’ at their shrines, where their ‘clean power’ triumphs over demons, magicians, illness, and death. They act, according to the expression of Gregory of Tours, as ‘the healing right hand of the divine power’ (medicabilis divinae potentiae dextera).

On closer examination, the exorcism of the possessed stands out as the most paradigmatic of this power. The potentia of the saint confronts the unclean power of the demon, who is submitted to an interrogation with ‘heavy judicial overtones’. In this spectacular drama of healing, after being constrained to reveal his true identity, the demon is forced to recognize the saint's superior potentia and leave the convulsing body of the possessed, who is thus reintegrated into the human community. Such a delivery from possession may be performed by a living ‘holy man’, but the possessed can also be healed in a similar manner near a shrine where a martyr-saint is claimed to be present. This second case allows further insight. The martyr was originally the victim of an unclean power, and by virtue of his passio he now becomes a judge invested with divine power. An oppressive judicial mechanism is thus transmuted into its reverse: In the exorcism of the possessed the demons will be tortured, forced to confess and repent, and the domination of divine power will be secured. And the power of the saints not only stands against that of the demons, but also corrects the evils of unjust secular power. It frees the prisoners and the condemned and prevents further persecution of the just.