This book discusses the unarticulated unconscious and tacit knowledge, termed “dark matter of the mind,” which underlies and enables verbal communication. Humans, when they speak or interpret, make use of a wide variety of skills and distinctions, in grammar, phonetics, organization of information by importance, and assumptions taken for given, for example, which compose this dark matter. The book’s contention is that this unconscious knowledge is not a product of innate human psychology, but rather of cultural influences and experiences. The book draws on the author’s experience attempting to translate the Bible and its cultural context for the Pirahãs in the Brazilian Amazon as a missionary activity. This missionary activity was hindered by a large number of underlying, largely unspoken, assumptions on the part of the American author on one side and the Pirahãs on the other which it impossible to translate the New Testament in such a way that it would be accessible for the Pirahãs in the same way that is to Americans. The author’s experience as a missionary, along with other studies of cultural conditioning, confirms an understanding of the individual which echoes the Buddhist concept of Anatman, which asserts that there is no innate human nature, but only the self which is entirely composed of memory and experience.