Halliday's investigations into grammatical metaphor take us deeply into the way we construct and expand meanings, starting with representations of concrete experienced events and ending with theoretical worlds populated by abstract entities linked through generalized relations and causalities. He finds these processes most strikingly in the development of the modern sciences that have historically created robust virtual worlds of theory from observable material events. He sees the same processes of grammatical metaphor as children learn to participate in our built symbolic environment, particularly as they are introduced to these meaning systems in schools, an institution designed expressly for that purpose.' Professor Charles Bazerman, University of California, Santa Barbara.