Combining the convenience of a dictionary with the depth of a history of philosophy, this new reference book fills a great need and should prove exceedingly useful to all students and scholars in classics, philosophy, theology and linguistics. The book defines and translates key terms used by pre-Christian philosophers up to the time of Proclus, with special references to the writings of the philosophers as they developed nuances and new meanings for the terms. Entries are arranged in dictionary style, but a knowledge of Greek is not necessary to use the book, since an English-Greek index provides the reader with Greek equivalents of English terms, with cross-reference to the main text. Its great value is that it isolates terms and allows the reader to follow their individual careers, while at the same time it offers an evolutionary history of the concept instead of a mere definition.