Hippocrates of Kos, also known as Hippocrates II, named after his grandfather Hippocrates I was a Greek physician and philosopher of the classical period who is considered one of the most outstanding figures in the history of medicine. He is traditionally referred to as the "Father of Medicine" in recognition of his lasting contributions to the field, such as the use of prognosis and clinical observation, the systematic categorization of diseases, and the formulation of humoral theory. His studies set out the basic ideas of modern-day specialties, including surgery, urology, neurology, acute medicine and orthopedics, and advanced the systematic study of clinical medicine.