People think about abstract domains like TIME and GOODNESS metaphorically. This tendency may be universal. Yet the particular mental metaphors that people use can differ dramatically between individuals and groups, and may change from one moment to the next. Where do our mental metaphors come from, and how can they change so quickly in response to new patterns of experience? If mental metaphors are grounded in universal patterns of body–world interaction, how can different people have contrasting (and sometimes contradictory) mental metaphors? Hierarchical Mental Metaphors Theory (HMMT) provides an account of: (a) how mental metaphors are formed and changed, (b) how they can be fundamental to our understanding of abstract domains, yet at the same time remarkably flexible, and (c) how distinctive language-specific, culture-specific, and body-specific mental metaphors can arise from universal patterns of interaction with the physical and social world.