In this book written for the layman, linguist George Lakoff and philosopher Mark Johnson cogently argue that metaphor is integral, not peripheral to language and understanding. Furthermore, "metaphor is pervasive in everyday life, not just in language but in thought and action. Our ordinary conceptual system, in terms of which we both think and act, is fundamentally metaphorical in nature." (p. 3)

The authors adopt a broad definition of metaphor, examine common phrases for metaphorical interpretation, and offer a classification system of metaphor. For example, orientational metaphors are found in our ordinary language and are part of the spatial organization of our lives. When one says, "He dropped dead" or "He's at the peak of health," one is using the orientational metaphor that we live by: "Health and life are up; sickness and death are down." This orientation is not arbitrary; the authors point out that one lies down when one is ill.

Other types of metaphors categorized by the authors are structural and ontological (e.g., making a non-entity into an entity: "We need to combat inflation," or setting a boundary on a non-entity: "He's coming out of the coma"). The authors also differentiate metaphor from other figures of speech, such as metonymy, which relies more completely on substitution: "The ham sandwich wants his check."

The second half of the book address issues more philosophical in nature, such as theories of truth and how we understand the world, including the "myths" of "objectivism," "subjectivism," and "experientialism." These theories are reviewed with metaphor in mind. For example, objectivism relies on the separation of man from the environment and the subsequent mastery over the environment. Hence objectivism is rife with metaphors which confirm such ideas as "knowledge is power."

The authors conclude by stating that metaphors provide "the only ways to perceive and experience much of the world. Metaphor is as much a part of our functioning as our sense of touch, and as precious."