Stoic work on ambiguity represents one of the most innovative, sophisticated and rigorous contributions to philosophy and the study of language in western antiquity. This book is both the first comprehensive survey of the often difficult and scattered sources and the first attempt to locate Stoic material in the rich array of contexts, ancient and modern, which alone can guarantee full appreciation of its subtlety, scope and complexity. It is designed to be intelligible to readers with no Greek or Latin.