Hippocrates was an Ancient Greek doctor. His ideas and books were very influential will into medieval times and beyond. He dismissed the idea that Gods caused disease - he believed there was a physical reason for illness, which needed a physical cure. Most of his treatments were based on diet, exercise and rest but he also used bleeding and purging to get red of excess humours. He wrote the Hippocratic Oath, where doctors swore to respect life and prevent harm. His method of clinical observation - studying symptoms, making notes, comparing with similar cases, then diagnosing and treating - is the basis of the approach used today