This book explains how the grammarians of the Graeco-Roman world perceived the nature and structure of the languages they taught. The volume focuses primarily on the early centuries AD, a time when the Roman Empire was at its peak; in this period, a grammarian not only had a secure place in the ancient system of education, but could take for granted an established technical understanding of language. By delineating what that ancient model of grammar was, the book highlights both those aspects that have persisted to this day and seem reassuringly familiar, such as ‘parts of speech’, as well as those aspects that are wholly dissimilar to our present understanding of grammar and language.