The Carmelite Bartolomé Xiberta (1897–1967) is one of the great theologians and religious historians of the 20th century. While his theological writings on synodality are currently experiencing a renaissance, his historical studies remain forgotten. Xiberta wrote a literary history of the Carmelite authors of the 14th century, who, although comparatively unknown, have important contributions to make to the debates that characterized this saeculum. The essay traces Xiberta’s life and focuses on his main theological work, the Clavis Ecclesiae, without which his work on the Carmelite authors would probably never have been written. His De scriptoribus scholasticis is at the center of the essay: it examines the circumstances of its creation, its content and its relevance for (current) historical studies. Finally, the reasons why this work fell into oblivion will be explored.