This article explores a dimension of the intense and complex intellectual relationship between Henri de Lubac and Michel de Certeau, as illustrated in the dialogue between Corpus Mysticum and The Mystical Fable. In particular, we focus on one branch of de Lubac’s intellectual project, which seeks to unearth the potential of medieval symbolism to counteract harmful aspects of modern rationality. This effort is inspired by a sacramental ontology and the centrality of the allegoria in factis, a legacy of the thought of the Church Fathers. Certeau’s reflection in The Mystical Fable proves to be not only the continuation of Corpus Mysticum but also tangentially reveals its limits through close attention to the nominalist rupture. Certeau shows that the emergence of modern mysticism in the 16th and 17th centuries came about as a response to allegoria in factis being displaced by allegoria in verbis, which is at the root of the deontologization of language and the schism between spiritual experience and theology.