Over the past half century metaphor has moved from being a peripheral topic in the philosophy of art to the status of a major philosophical, linguistic, psychological, and scientific issue in the theory of cognition. For over 2,000 years prior to this dramatic change of status, metaphor was regarded as nothing more than a figure of speech serving various rhetorical purposes, but not an essential part of human thought. In sharp contrast, contemporary empirical research on language and cognition affords metaphor pride of place at the center of abstract conceptualization and reasoning. This new view appears to require a serious reconsideration of some of the grounding assumptions of mainstream philosophy of mind and language.