IAN JOHNSTON was born at Collaroy, NSW in 1939. An eminent neurosurgeon, he was appointed a member of the Order of Australia (AM) in 2000 for services to medicine. Throughout his medical career Ian also pursued a life-long passion for ancient languages, completing degrees in Greek and Latin, and in classical Chinese at the Universities of New England and Sydney. His translations of Chinese poetry have been performed at arts festivals and exhibitions and he has made several radio and television appearances to discuss aspects of translation.

• Part I. Introduction: 1. General introduction; 2. Galen's life and works; 3. Galen's philosophical and medical antecedents; 4. Definitions and terminology: i. Definitions; ii. Causal terms; iii. General terms; iv. Diseases and symptoms; v. Conclusions; 5. The classification of diseases and symptoms: i. Introduction; ii. Diseases (de morborum differentiis); iii. Symptoms (de symptomatum differentiis); iv. Conclusions; 6. Causation in diseases and symptoms: i. Introduction; ii. Theories of disease causation prior to Galen; iii. Galen on causation; iv. Conclusions; Part II. Translation: Introduction; 1. On the differentiae of diseases; 2. On the causes of diseases; 3. On the differentiae of symptoms; 4. On the causes of symptoms I; 5. On the causes of symptoms II; 6. On the causes of symptoms III; Part III. Conclusions; Bibliography.