In time, a lore accumulated that was passed from generation to generation. After centuries of such transmission, the knowledge of herbal ingredients became distilled and refined. We find the basic theories of herbal medicine already well developed in texts that date to the second century BCE discovered at Ma Wang Dui in Chang Sha in Hunan province. This system of classification was based upon the theory of yin and yang. Perhaps more importantly, the art of herbal medicine has always been intimately linked with the art and science of macrobiotics or life extension in China.
Herbs are first and foremost foodstuffs that nourish the body in precise and well-defined ways.
The lore of Chinese herbal medicine is vast and occupies literally thousands of ancient classics. In the West we have only scraped the surface of this vast literature, but with a growing number of people hungry for herbal medicine, we will no doubt witness an increase in the appearance of such information over the years to come. In China, where knowledge of Chinese herbs is widespread, people frequently self-prescribe herbal medicines for common complaints. But even in China, whenever there is a severe medical condition, people seek out the guidance of a properly trained practitioner. Herbal medicines, though notably free of side effects as a general rule, can produce unwanted results.