Theory of diseases treated with cassia twig decoction

Chinese woodcut illustration from an edition of 1833 (13th year of Daoguang reign period of Qing dynasty). The image and text give an account of the principles of diseases treated with cassia twig decoction, and the therapeutic effects of the individual ingredients of this remedy. The bladder channel of foot taiyang runs along the back of the body, connecting with the lungs at the top and the kidneys at the bottom. When wind-cold malignance attacks the upper body, this generally results in stiffness and swollen glands in the neck; when they attack the lower body, this generally leads to pain and swellings in the lumbar region. Cassia twig decoction is used to treat exterior deficiency syndrome of the taiyang channel characterised by spontaneous sweating. Cassia twigs are pungent-warm (xinwen), and serve to disperse wind-cold malignance in the taiyang channel. The decoction also contains Chinese herbaceous peony (shaoyao), which is bitter-cold and serves to harmonise nutrient Qi (yingqi) and arrest sweating; Chinese dates (da zao), which are sweet in flavour and enhance the nutrient-harmonising effects of the Chinese peony; ginger, which is pungent in flavour and serves to assist defensive Qi (weiqi) and release the muscles; and liquorice, which harmonises the various ingredients, regulates 'middle Qi' (zhongqi), and harmonises external and internal factors.

At the top it connects with the lung, viz. at fengfu (Storehouse of Wind), therefore there is generally pain and swelling in the neck; at the bottom, it connects with the kidneys, therefore there is generally back-ache. The taiyang (Great Yang) channel runs along the back of the body. The main ingredient is cassia twigs. Chinese herbaceous peony (shaoyao) serves to harmonise nutrient Qi. Chinese dates serve to assist nutrient Qi. Ginger serves to assist defensive Qi. Liquorice harmonises all the ingredients.