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Bai Zhi (Angelicae Dahuricae Radix), with a pungent flavor and warm temperature, is ascending and yang in nature, and non-toxic. It enters the Foot-Yangming and Hand-Yangming meridians, and also the Hand-Taiyin meridian. It treats headache, resolves wind-stroke due to cold-heat, stops metrorrhagia and metrorrhagia (abnormal uterine bleeding) and leukorrhea (red and white vaginal discharge), unblocks blood obstruction, disperses itching in the eyes, stops dysentery, eliminates mass (zhijia), serves as a general medicine for treating wind disorders, stabilizes blood pain in the heart and abdomen, and is especially effective for external treatment of various sores, carbuncles, hemorrhoids, and fistulas; it detoxifies and generates flesh, kills snakes and insects. This herb can serve as a minister or guide drug but should not be relied upon as a sovereign drug; only in external use can it serve as a sovereign drug. Since Bai Zhi is pungent and dispersing, excessive consumption may deplete primordial Yang.

One might ask: Bai Zhi dissipates Qi; is it not feared that external use will cause harm? Why do you worry so deeply? The efficacy of this herb can be verified during its preparation and combination. I have an excellent method to distinguish it. When purchasing Bai Zhi for medical treatment, its color is always white. Upon bringing it home for preparation, if it suddenly turns black, it should not be used; if it turns slightly yellow, it has half efficacy; if it turns old yellow, it has little efficacy; if it turns dark yellow, it has no efficacy. By identifying the white ones, using them in larger quantities will lead to recovery. Otherwise, following the order of inferior drugs, how could external use dissipate true Qi? This herb is particularly efficacious, hence its tendency to change color. Experienced physicians naturally know this; it is not a novel theory.

Xi Xin (Asari Radix et Rhizoma), with a strongly pungent flavor and warm temperature, is ascending and yang in nature, and non-toxic. It enters the Foot-Shaoyin and Hand-Shaoyin meridians. It stops headache with divine efficacy, treats various rheumatic bi-syndromes, and is especially beneficial to the Liver and Gallbladder meridians. The Kidney becomes warm upon receiving it. It opens orifices, clears phlegm, stops tearing caused by wind exposure, treats blood obstruction in women, and dispels interior cold pathogens. For bad breath and swollen teeth, gargling is also effective. However, it should only be used in small doses and not in large amounts; it can only be used in combination and not alone. Excessive use leads to Qi depletion and increased disease; solitary use leads to exhaustion of Qi and death. Can one not be cautious?

One might ask: Since Xi Xin can warm the Kidney, it is naturally a tonic; why does it dissipate Qi? Xi Xin is a Yang drug, ascending and not sinking. Although it descends to warm the Fire in the Kidney, it does not warm the Water in the Kidney. The nature of Fire is to flare upwards; Xi Xin warms the Fire and thereby guides the Fire to ascend. This is why it should not be used in large quantities.

One might ask: If Xi Xin dissipates true Qi, how can it be effective for headache? The head is the summit of the Taiyang; when clear Qi ascends and turbid Qi descends, the head and eyes feel refreshed. Only when turbid Qi ascends and clear Qi descends do the head and eyes feel heavy and prone to pain. Xi Xin has a clear, non-turbid aroma, thus it excels at descending turbid Qi and ascending clear Qi, which is why it treats headache with divine efficacy. However, since its flavor is pungent and its nature is dispersing, it must be assisted by blood-nourishing herbs to prevent the Qi from dispersing.