Catholic relics elicit strong emotion and are thought to have healing powers; they are an important part of Catholic practice, yet their affect is not often explicitly explored. Arguing that relics are affective, or emotionally impactful, because they are part of a system that encourages intense emotional reactions through sensation and perception, this thesis examines the transmutability of Catholic relics and their emotional impact beyond religious doctrine using an interdisciplinary theoretical framework of affect, emotion and empathy. Locating Catholic practice within a twentieth-century Quebec context in the form of a case study, this investigation of affect is situated through events surrounding the display of the relic heart of Brother André in the 1970s as well as his larger healing ministry. Utilizing discourse and media analysis methods and set against the historical background of the body and physicality in Catholicism, an overview of the sensory and emotional history of relics, and the emotional attachment of the faithful to the saints, this thesis concludes that the positive affect generated by Catholic relics is transmissible to non-Catholics, as humans are susceptible to empathic contagion.