Critique of Pure Reason

Human reason, in one sphere of its cognition, is called upon to consider questions, which it cannot decline, as they are presented by its own nature, but which it cannot answer, as they transcend every faculty of the mind.

Critique of Pure Reason by Immanuel Kant is one of the most influential works in the history of philosophy. Also referred to as Kant's "first critique," it was followed in 1788 by the Critique of Practical Reason and in 1790 by the Critique of Judgment. In the preface to the first edition Kant explains what he means by a critique of pure reason: "I do not mean by this a critique of books and systems, but of the faculty of reason in general, in respect of all knowledge after which it may strive independently of all experience."

The great systems of Fichte, Schelling, Hegel, Herbart, and Schopenhauer branched off from Kant, and now people begin to see that those systems were indeed mighty branches, but that the leading shoot of philosophy was and is still Kant.