First published in 1985 (MIT Press), Fauconnier's influential book, Mental Spaces, was instrumental in shaping the new field of cognitive linguistics. The concept of mental spaces--that we develop constructs during discourse that are distinct from linguistic constructs but are established by linguistic expressions--provides a powerful new approach to problems in philosophy and cognitive science concerning thought and language. It includes a new preface that provides context for the theory, and a new foreword by George Lakoff and Eve Sweetser (both of U.C. Berkeley).