Huang Di asked, "Can you please discuss more about the principles governing the art of herbal therapy?"

Qi Bo replied, "In general, mild conditions require a small formula with light-flavored herbs, while acute and severe conditions demand a large formula with thick-flavored herbs. When treating conditions of the upper body one should use more radical herbs while for the lower body gentle herbs would be more appropriate. An herbal decoction should be consumed before meals for conditions located in the lower part of the body, and after meals for conditions in the upper part of the body. One should treat the exterior first when a condition began on the exterior and then attacked the interior. The reverse is true: when a condition originated on the interior and then progressed to the exterior, the interior should be addressed as a priority. Often when a heat condition does not respond after the use of cold or cooling herbs it is because the nature of the illness was not accurately established. Remember: discover the true nature of an illness before embarking on any treatment. Adherence to these general rules will enhance the success of the treatment."

Huang Di asked, "Can you tell me about the three grades of herbs that were recorded in the Shen Nong Ben Cao [Shen Nong's Materia Medica]?"

Qi Bo replied, "In ancient times the art of herbology was practiced by categorizing all herbs into three classifications. The first category of herbs was called superior, or immortal, foods because of their lack of side effects and strengthening qualities. These were often incorporated into one's diet and were used as preventive measures. The second category of herbs was called medium or medicinal and were used to rectifying imbalances in the human body. These were used until the patient recovered from their illness and then withdrawn. The third category of herbs was called inferior or radical herbs, so named because they are strong in action and not without side effects; sometimes they are toxic. Therefore these were used often in small amounts and once the desired action took place they were discontinued immediately.

"The paramount mission in healing is to dispel the pathogen and strengthen the patient."

Huang Di said to Qi Bo, "Thank you. This discussion has been most revealing."