Helmholtz's objections to Kant concerning the origin and meaning of geometrical axioms were influential in the later philosophical debate on the relationship between space and geometry. However, the discussion of Kant's Transcendental Aesthetic in neo-Kantianism was rooted in earlier objections formulated by such philosophers as Kant's successor at the University of Königsberg, Johann Friedrich Herbart, and the neo-Aristotelian Adolf Friedrich Trendelenburg. This chapter is devoted to the discussion of these objections in the early works of the founder of the Marburg School of neo-Kantianism, Hermann Cohen. Cohen's defense of Kant was based on a sharp distinction between the psychological and the transcendental method: the aprioricity of some knowledge does not depend on our mental faculties, but rather on its role in the constitution of the objects of experience. In order to clarify this point, Cohen identified experience in Kant's sense as scientific knowledge. His reading of Kant suggests that the search for the conditions of experience depends on the history of science. Since this consequence was made explicitly by Cohen's student, Ernst Cassirer, the concluding section deals with Cassirer's considerations in support of Cohen's reading of Kant. These considerations were strictly related to Cassirer's interpretation of the logic of knowledge in the history of science.