Aconite and Asarum: Root-Branch Relations of Shaoyin and Taiyang
Aconite and asarum are placed within the root–branch relationships of the Three Yin and Three Yang. Both are closely related to Shaoyin, yet through the exterior/interior and root/branch relation between Shaoyin and Taiyang they can also influence outer layers and Taiyang-related manifestations.
Aconite is commonly understood as a Shaoyin medicine capable of returning to the root of Fire and Yang qi; at the same time it can assist Shaoyang Fire-Heat and benefit the Taiyang branch. Asarum is summarized as an important medicine of “Shaoyin as root, Taiyang as branch.” Its treatment of wind-damp painful impediment, contraction of the hundred joints, headache, and brain pain seems scattered on the surface but can be returned to the linkage between Shaoyin root qi and the Taiyang branch layer.
We note that many of the reasoning rules for asarum can be traced to “The Channels” in the Lingshu and the “Treatise on Impediment” in the Suwen. This suggests that the ancients did not use asarum merely because they saw headache, but reasoned from Shaoyin, Taiyang, the channels, and obstruction to the various indications.