This essay finds its departure point in a title page that Aby Warburg (1866 – 1929) drafted for his lecture on the Pueblo Indians. Through the labyrinthine thought pathways evidenced by this much-amended and overwritten typescript, it explores the relation between reason and mania in Warburg's thought specifically and in humanistic scholarship more generally. Composed in 1923 while Warburg was committed to the Bellevue mental sanatorium in Kreuzlingen, Switzerland, the title page, and the lecture that it attempts to name, belong to their author's profound and influential meditations on the defensive function of rituals and symbols. More practically, the lecture was intended, by its successful drafting and delivery before an audience of inmates, doctors, and professional colleagues, to prove Warburg's sanity and secure his release. Through an investigation of the outbreak and symptoms of Warburg's psychosis, which uncannily prefigure real historical terrors, this article represents the lecture as (in Warburg's words) a powerful “seismograph” of the European soul. Placing us at Warburg's writing desk at the pivotal moment of the author's cure-by-writing, the title page also illuminates the legacy of Warburg's Library, today at the core of the Warburg Institute in London, since the crisis that the page documents — larger than Warburg's personal one — still lies at the heart of humanistic scholarship as it attempts to grasp the essence of what it means to be human.