‘Water mixed with the blood of Thomas’: contact relic manufacture pictured in Canterbury Cathedral’s stained glass

Four remarkable stained glass panels in the Trinity Chapel of Canterbury Cathedral (executed c.1185–1220) picture the mixing of Thomas Becket’s blood with water at Becket’s tomb. The ‘water of St Thomas’ was among the most widely renowned medieval water relics, reputed to have healed the sick throughout Latin Christendom. This article examines the glass images, comparing them with narratives in the glaziers’ source text, Benedict of Peterborough’s collection of Becket’s miracles. The glaziers presented an enhanced and carefully designed version of the early history of the water relic: the visual images draw strong parallels between the water of St Thomas and the Eucharist, and trumpet the role of the monks of Christ Church Cathedral Priory, Canterbury, the patrons of the glass, in the mixing process. The glass panels also provide suggestive evidence regarding the personnel, vessels and ceremonial involved in the actual mixing of the relic at Canterbury, including the likely participation of a lay sacrist and the possible use of mazers.