The radicalisation of Kant’s critical philosophy by the Jena Romanticism and, above all, by Novalis, is decisive for the understanding of the modern relationship between philosophy and poetry (i.e. literature or, more generally, art), which is both a relationship of continuity and rupture: such is the starting hypothesis of the study. The shared horizon, but also a matrix of the ambiguous relationship of philosophy and poetry, is the turn I venture to describe as a transition from ontology to ontogony. After Kant, ontology became a field of modal orientation: the world is a necessary world. The world is becoming a task. The study delves into the conceptual depth of this turn, respectively of the relation between philosophy and poetry, based on the reading of Kant’s critical philosophy proposed by Gilles Deleuze. The analysis sets itself the task of highlighting unexpected yet crucial dimensions of the complex relationship between philosophy and literature, established in modern terms only in the second half of the 18th century. The figures of “Reason” and “Madness”, expressing the immanent tension of Kant’s productive power for imagination, will occupy a central place among them.