First published in 1689, "An Essay Concerning Human Understanding" is British philosopher John Locke's important and influential exposition on the foundation of human knowledge and understanding. Arranged into four books, the first book begins by rejecting the notion of innate ideas proposed by Descartes and proposes instead that humans are born as blank slates. Book two argues that all knowledge is derived from experience and reflection. Locke also makes the argument for the existence of an intelligent creator or God. Book three addresses language and the unique ability that humans have to assign sounds to meanings and objects and then arrange those words into a language. Locke criticizes the careless use of language by some philosophers and how it can lead to confusion and misunderstanding. Book four is a detailed examination of human knowledge, intuition, mathematics, moral philosophy, natural philosophy, faith, and opinion.