Anecdotal evidence from literacy educators sometimes suggests that many people can do well despite being illiterate; however, this perspective ignores the essential theory of literacy. This theory rests on the premise that the most essential difference between human beings and other creatures is the human ability to make "symbolic transformations." Today the capacity to deal with symbolic transformations (writing) is almost universal. Literacy then can be justified in terms of its essential nature. So construed, literacy is self-justified: literacy for the sake of literacy, as a fulfillment of the human biosocial destiny, and therefore, as a human right. Literacy is "potential added" to newly literate people. The essential theory of literacy is linked with the concept of"symbolic capital." This refers to the body of knowledge made possible by literacy that can be owned by individuals, groups, and cultures. An equitable distribution of societal knowledge capital is part of the distributive justice and of the moral social order being sought today. Implications of this theory are that: (1) literacy should be promoted as an essential human right; (2) programs of "literacy advocacy" should precede programs of "literacy teaching"; and (3) evaluation of the effects of literacy in the informal economy and evaluation of customer satisfaction are important. (KC)