This book gives a clear and thorough description of three fascinating linguistic projects that were carried out in the seventeenth century: the philosophical languages of George Dalgarno (1661) and John Wilkins (1668), as well as the work of Leibniz in this area. These projects combined practical purposes, such as improving communication, with profound theoretical insights concerning the representation of knowledge and the nature of language. Rich in detail, this book provides all the material for a proper understanding of the workings of these schemes, while illuminating the intellectual context in which they took shape. It will be welcomed by anyone interested in the history of linguistics and philosophy of language. This book: - offers in-depth analysis of the two most sophisticated universal language schemes created in the seventeenth century: the philosophical languages of Dalgarno and Wilkins, supplementing existing literature in focusing on the internal details of the languages, highlights and documents the controversy between Dalgarno and Wilkins, largely ignored in most other books on the subject, showing that their schemes resulted from different, and in various respects antagonistic approaches, presents a careful account of Leibniz's plans for a philosophical language, and illustrates, in discussing his philosophy of language, how his thought was formed in constant interaction with contemporaries, discusses at greater length than usual the extensive work Leibniz did in carrying out his plans, and shows to what extent he was indebted to Dalgarno and Wilkins, emphasizes the importance of the logical tradition for the structure of artificial languages constructed in the seventeenth century, and clarifies the role played by dominant views of the relation between spoken and written language, maintains a fine balance between historical research and argument, presenting what was said as accurately as possible and placing it within its proper context, but also attempting to evaluate the views described, is of interest to linguists, philosophers and historians of ideas.