An Essay Concerning Human Understanding

John Locke's inquiry into the foundations of human knowledge treats the newborn mind as a blank slate on which experience later writes, though he never used the words tabula rasa. Book I attacks the rationalist doctrine of innate ideas, arguing, among other points, that no truth wins everyone's assent. Book II traces every idea to sensation or reflection, separating simple ideas such as red or sweet from complex ones such as number, cause and identity, and primary qualities such as shape from secondary ones. It also offers a largely psychological view of personal identity. Book III concerns language and Book IV knowledge, faith and opinion. The Essay became a principal source of empiricism and shaped George Berkeley and David Hume.

Mark Manson called it the foundation of empiricism, the competing school of thought in the Enlightenment.