The Critique of Pure Reason is one of the most influential works in the history of philosophy and marks a turning point and the beginning of modern philosophy. Also referred to as Kant's "first critique, " it was followed by the Critique of Practical Reason and 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. " Immanuel Kant (1724-1804) was a German philosopher, who, according to the Stanford Encyclopedia of Philosophy is "the central figure of modern philosophy. " Kant argued that fundamental concepts of the human mind structure human experience, that reason is the source of morality, that aesthetics arises from a faculty of disinterested judgment, that space and time are forms of our understanding, and that the world as it is "in-itself" is unknowable. Kant took himself to have effected a Copernican revolution in philosophy, akin to Copernicus' reversal of the age-old belief that the sun revolved around the earth.