This volume explores the consequences for syntax of assuming that language is grounded in cognition and perception. It shows that syntax is characterized by a set of categories based on distinctions in what the categories are perceived to represent. The first part of the book traces the twentieth-century development of anti-notionalism, culminating in the assumption that syntax is autonomous. The author then looks at syntactic phenomena, many involving the fundamental notion of finiteness. He considers whether the appeal to grounding permits a lexicalist approach that would allow syntax to dispense not only with structural mutations such as category-change and 'empty categories' but with universal grammar itself.