A major revolution in the study of metaphor occurred 30 years ago with the introduction of "conceptual metaphor theory" (CMT). Unlike previous theories of metaphor and metaphorical meaning, CMT proposed that metaphor is not just an aspect of language, but a fundamental part of human thought. Indeed, most metaphorical language arises from preexisting patterns of metaphorical thought or conceptual metaphors. This article provides an evaluation of the linguistic and psychological evidence supporting CMT, and responds to some of the criticisms of CMT offered by scholars within cognitive science. Some new ways of thinking of conceptual metaphors from the perspective of embodied simulations and dynamical systems theory are also presented.