Mapping Knowledge: The Preliminary Discourse

D'Alembert's Preliminary Discourse, which opened the Encyclopédie in 1751, explained how all human knowledge fits together. Borrowing from Francis Bacon, he divided knowledge according to three faculties of the mind: memory, which produces history; reason, which produces philosophy and science; and imagination, which produces the arts. An accompanying chart, the 'Figurative System of Human Knowledge', showed these branches as a tree.

The arrangement made a quiet but radical statement: theology appeared as one branch under reason and philosophy, not as the crowning queen of the sciences it had been in medieval universities. D'Alembert also praised Bacon, Descartes, Newton and Locke as the founders of modern thought, creating a heroic genealogy for the Enlightenment. Readers could see from the structure itself that knowledge now rested on experience and reason. The Discourse thus served as both an introduction and a manifesto.