Critique of the Kantian Philosophy
"Critique of the Kantian Philosophy" (German: "Kritik der Kantischen Philosophie") is a 143-page essay which Arthur Schopenhauer appended to the first volume of his The World as Will and Representation (1818). He wanted to show Immanuel Kant's errors so that Kant's merits would be appreciated and his achievements furthered.
Source: Wikipedia — Critique of the Kantian Philosophy (CC BY-SA 4.0)