To the monastery at Canterbury and the universal church, Brother Roger de Berkeley[992] sends greetings.

We accept the report of the beloved brought now before you: that he was troubled by a demon [and] as he was scorned by the people of the community, he roamed foolishly as one of the beasts in the wild.

This letter was sent to the monks of Christ Church, Canterbury, and copied into the twelfth-century miracle collection compiled there by William of Canterbury, one of the shrine custodians responsible for recording the mira­cles that took place at the tomb of Saint Thomas Becket. It relates the story of a man who was believed to have been ‘troubled by a demon' (‘a daemonio fuisse vexatum'). The man's possession led to him being cast out of his community, and reduced to the state of a wild beast. Only the intercession of the saint could restore him to the local population, who then bore testimony to his cure.

This chapter sets up a case study, which uses the twelfth-century miracles of Saint Thomas Becket to explore the relationship between the possessed, the demons who possessed them, and the saint who cured them. In Becket's recorded miracles, the condition most often (though not exclusively) asso­ciated with demonic interference was madness. Madness affected the body, mind and soul, and any study of demonic madness must therefore consider the physical, mental, and spiritual capabilities of demons, and the ways in which they were able to “possess” their victims. I contrast representations of the interaction between demons and the possessed with instances of contact made between saints and mad pilgrims. This approach offers an innovative insight into how the body, mind, and soul were understood within the context of the miraculous, and how humanity was thought to differ from and interact with the supernatural and spiritual presences that existed alongside it.

By concentrating on possession and madness in the twelfth century, this chapter builds on several recent studies. Nancy Caciola has examined medi­eval distinctions between divine and demonic possession, focusing largely on the possession of women in the late-twelfth to fifteenth centuries. She uses hagiographies, handbooks, encyclopaedias, demonologies, and scholastic treatises, as well as other sources, to examine the ‘long-term labour of social interpretation' that was the discernment between false prophets and divinely- inspired women.^[994] Caciola's consideration of a range of sources in relation to spirit possession is particularly useful in light of her own discernment between the self-representation of the possessed and the evaluation of their conditions by their communities.^[995] With the growth of mysticism in the later Middle Ages, and the increasing attention paid by late medieval writers to female piety, the discernment of spirits (the practice of differentiating between good and bad spirits, or between divine and demonic possession) was particularly motivated towards protecting women, who were deemed more susceptible to demonic trickery, from going astray.^[996] Renate Blumenfeld-Kosinski makes a connection between this pre-occupation with the discernment of spirits, and religious anxieties of the later Middle Ages, when women were becoming increasingly involved in spiritual pursuits and as the European witch-hunt was approach­ing in centuries to come.^[997] Alain Boureau argues that, rather than a continued fascination with and fear of the demonic existing throughout the Middle Ages, a sudden interest was sparked between 1280 and 1330, which then led to the witch hunts of the fifteenth century.^[998] He contends that, in the twelfth century, possessions were often recorded as passive experiences by hagiographers, and were frequently connected with madness, a connection also seen in other contemporary writings, as will be discussed below.^[999] It is perhaps because of our retrospective awareness of the witch-hunt that historians have focused on tracing the connection between demons, women, and magic in the later Middle Ages, and have overlooked twelfth-century texts in which the repre­sentation of demonic possession was very different.^[1000] The emphasis in hagi­ographies of this period was not on the discernment of a good or bad spirit, but on the power of a saint to exorcise bad spirits, in order to accentuate his/ her holiness. Diagnosis, or discernment, of possession was sometimes vague, though diagnostic ambiguity was not unique to hagiography.

In Demons and Mental Disorder in Late Medieval Medicine, Catherine Rider draws attention to the growing willingness in some medical texts, such as Constantine the African's Pantegni, which drew on Arabic and Greek medi­cal traditions, to entertain the idea that mad patients might have had spe­cial abilities (see below), which were potentially influenced by demons.^{[1001] [1002] As Anne E. Bailey demonstrates in her chapter in this volume, it is anachronistic for modern historians to equate the “demonic” with the “non-medical”. Rider notes that saints' lives frequently cited multiple causes for madness and that it was often difficult to distinguish which cases had been caused by demonic possession and which had not.11 The blurred boundaries between humoral and demonic diagnoses for madness call for a further examination of the role that both demonic aetiologies and traditional medical theories played in the conceptualisation and representation of madness in twelfth-century hagiog­raphy. Thomas Becket's miracles have been chosen as the focus of this case study because the extensive miracle records that were produced at Canterbury provide a large enough sample of cases of demonic possession that similarities and differences between different miracles can be examined.}

Two collections were made at Canterbury Cathedral in the 1170s of the mir­acles of Thomas Becket who was canonised by Pope Alexander iii in 1173. The collections are the largest surviving compilations of miracle stories from twelfth-century England, and contain the records of around 703 miracles. Both compilers were in Canterbury at the time of the martyrdom of Thomas Becket, who was killed in Canterbury Cathedral on 29 December 1170, though neither was an eyewitness. William of Canterbury, in fact, admitted, with some regret, that he and others had fled the scene, since they were unworthy of mar­tyrdom.^{[1003] [1004] [1005] [1006] [1007] [1008] When the tomb of the martyr was opened to pilgrims after Easter 1171, Benedict of Peterborough was appointed as shrine custodian and began to record Becket's miracles.}

In June 1172, as the number of pilgrims visiting the tomb increased, Benedict was joined by an assistant, William of Canterbury. William was relatively new to the priory, having been ordained deacon by Becket himself in 1170 but was keen to prove his worth. Koopmans has analysed William's use of “medical” terminology and ideas, concluding that he at least had some knowledge of ancient medical writers, like Galen, even though he may not have read them first-hand.1⁴ William's descriptions of conditions often involve fairly com­plicated medical language, which was not seen in other contemporary mir­acle collections, including Benedict of Peterborough's?⁵ For instance, before relating the miraculous cure of an epileptic nun called Petronella, William explained that three types of epilepsy existed: ephilensia, which affected the brain, catalempsia, which began in the hands, arms and legs, and analempsia, which agitated the stomach?⁶ These three terms originated in Ancient Greece and were passed down from Galen?⁷ Nonetheless, in this chapter, I argue that, though William of Canterbury possessed knowledge of learned medical theo­ries such as these, they were not the sole influence on his discussion of illness. The demons that frequent his collection should not be viewed as the antithesis of these medical definitions of disease but rather as part of William's overall conception of health and sickness, which was based on his understanding of the relationship between body, mind, and soul.