An Essay Concerning Human Understanding John Locke - An Essay Concerning Human Understanding is a work by John Locke concerning the foundation of human knowledge and understanding. It first appeared in 1689 (although dated 1690) with the printed title An Essay Concerning Human Understanding. He describes the mind at birth as a blank slate (tabula rasa, although he did not use those actual words) filled later through experience. The essay was one of the principal sources of empiricism in modern philosophy, and influenced many enlightenment philosophers, such as David Hume and George Berkeley.Book I of the Essay is Locke's attempt to refute the rationalist notion of innate ideas. Book II sets out Locke's theory of ideas, including his distinction between passively acquired simple ideassuch as "red," "sweet," "round"and actively built complex ideas, such as numbers, causes and effects, abstract ideas, ideas of substances, identity, and diversity. Locke also distinguishes between the truly existing primary qualities of bodies, like shape, motion and the arrangement of minute particles, and the secondary qualities that are "powers to produce various sensations in us" such as "red" and "sweet." These secondary qualities, Locke claims, are dependent on the primary qualities. He also offers a theory of personal identity, offering a largely psychological criterion. Book III is concerned with language, and Book IV with knowledge, including intuition, mathematics, moral philosophy, natural philosophy ("science"), faith, and opinion.

John Locke was an English philosopher. Locke is considered the first of the British Empiricists, but is equally important to social contract theory. His ideas had enormous influence on the development of epistemology and political philosophy, and he is widely regarded as one of the most influential Enlightenment thinkers and contributors to liberal theory. His writings influenced Voltaire and Rousseau, many Scottish Enlightenment thinkers, as well as the American revolutionaries. This influence is reflected in the American Declaration of Independence.Locke's theory of mind is often cited as the origin for modern conceptions of identity and "the self", figuring prominently in the later works of philosophers such as David Hume, Jean-Jacques Rousseau and Immanuel Kant. Locke was the first Western philosopher to define the self through a continuity of "consciousness." He also postulated that the mind was a "blank slate" or "tabula rasa"; that is, contrary to Cartesian or Christian philosophy, Locke maintained that people are born without innate ideas.