The Vatican’s mediums. The strange case of Pope Pius IX and the spiritualistic experiences of the archbishop of Rennes

In the second half of the nineteenth century, the Vatican addressed Spiritualism through a series of decrees, with prominent Roman theologians framing it as a diabolical plot aimed at undermining the Church. This polemic contributed to new narratives of the ‘esoteric Other’ that shaped the religious mnemohistory of Western societies. Yet, key aspects of this confrontation remain obscure. Around the time of Kardec’s condemnation in 1864, Pius IX allegedly commissioned the archbishop of Rennes to carry out an empirical and confidential investigation into spiritualistic phenomena involving young children. Drawing on sources from the Vatican archives, this article reveals how the Holy See adopted a multi-layered strategy aimed not only at combating Spiritualism but also at understanding its phenomena. The findings shed light on the Church’s approach, highlighting the complexity and diversity of its institutional response and offering new insights into the interaction between established religion and alternative spiritualities in the modern West.