He was the first doctor to recognize that disease was associated with environmental factors, diet, and living habits. It seems so commonplace now, but back in 460 BC this was an interesting idea.
Hippocratic therapy followed nature and believed in the healing power inherent in nature which is still one of the main principles in naturopathic medicine... I even have this statement as a tattoo on my foot (the only tattoo I have!). In a time when people didn't understand disease or even their own body, Hippocrates showed a deep connection and profound wisdom that is just as valid today as it was many centuries ago.
The Hippocrate's Koan School of Medicine was, in a sense the first holistic medical school with the emphasis on patient care. Although, there was much more to learn about diagnosis, biochemistry, physiology, anatomy, and medications, Hippocrates core values are still used as a foundation for medicine and patient care.