The 'history of ideas', better known these days as intellectual history, is a flourishing field of study which has been the object of much controversy but hardly any historical exploration. This major new work from Donald R. Kelley is the first comprehensive history of intellectual history, tracing the study of the history of thought from ancient, medieval and early modern times, its emergence as the 'history of ideas' in the 18th century, and its subsequent expansion. The point of departure for this study is the perspective opened up by Victor Cousin in the early 19th-century on 'Eclecticism' and its association with the history of philosophy established by Renaissance scholars. Kelley considers a broad range of topics, including the rivalry between 'ideas' and language, the rise of cultural history, the contributions of certain 19th- and 20th-century practitioners of the history of ideas in interdisciplinary areas of philosophy, literature and the sciences, and finally the current state of intellectual history. The central theme of the book is the interplay between the canon of philosophical thought and the tradition of language and textual study, the divergence of the latter marking the 'descent of ideas' into the realm of cultural history.