Enlightenment historiography began in the period itself, from what Enlightenment figures said about their work. A dominant element was the intellectual angle they took. D'Alembert's Preliminary Discourse of l'Encyclopédie provides a history of the Enlightenment which comprises a chronological list of developments in the realm of knowledge – of which the Encyclopédie forms the pinnacle. In 1783, Jewish philosopher Moses Mendelssohn referred to Enlightenment as a process by which man was educated in the use of reason. Immanuel Kant called Enlightenment "man's release from his self-incurred tutelage", tutelage being "man's inability to make use of his understanding without direction from another". "For Kant, Enlightenment was mankind's final coming of age, the emancipation of the human consciousness from an immature state of ignorance." The German scholar Ernst Cassirer called the Enlightenment "a part and a special phase of that whole intellectual development through which modern philosophic thought gained its characteristic self-confidence and self-consciousness". According to historian Roy Porter, the liberation of the human mind from a dogmatic state of ignorance is the epitome of what the Age of Enlightenment was trying to capture.