This book provides a precise and thorough description of the meaning and use of spatial expressions, using both a linguistics and an artificial intelligence perspective, and also an enlightening discussion of computer models of comprehension and production in the spatial domain. The author proposes a theoretical framework that explains many previously overlooked or misunderstood irregularities. The use of prepositions reveals underlying schematisations and idealisations of the spatial world, which, for the most part, echo representational structures necessary for human action (movement and manipulation). Because spatial cognition seems to provide a key to understanding much of the cognitive system, including language, the book addresses one of the most basic questions confronting cognitive science and artificial intelligence, and brings fresh and original insights to it.