 Lange thought that materialism faced serious problems; however, he also thought that Hegelian idealism was bankrupt. What was needed was a philosophical approach that would be compatible with the recent successes of materialistic explanations as deployed by the natural sciences but not simply be a form of materialism. Lange was one of the first in this period to argue that the appropriate response to the philosophical situation in Germany at the middle of the nineteenth century was to return to Kant. (See Widmer, forthcoming, for a new evaluation of Lange’s positions on Kant. Beiser (2014) contains a careful appreciation of Lange as a central figure in the “Coming of Age” of Neo-Kantianism; see Patton (2015) and Edgar (2015) for reviews of Beiser.) As Lange put it in a letter, “I take the Hegelian System to be a step backward towards Scholasticism from which we are really already free. Herbart, to whom I first attached myself, was for me only a bridge to Kant, to whom so many honest researchers return in order to, where possible, complete what Kant had only half done: the annihilation of metaphysics” (Ellissen 1894, 106). Lange was thus one of the founding figures in what was to emerge as the neo-Kantian movement rallied by Otto Liebmann’s slogan “Back to Kant!”