肝 實 肺 虛 瀉 火 補 水 之 道 Tao of depleting fire and supplementing water
75th difficulty explains how to treat excess and deficiency. This difficulty is linked to difficulty 81 which also explains how to prevent disease produced by supplementing excess and depleting deficiency.
Difficulty 75 gives an example of excess of Liver and deficiency of Lungs.
Depleting the heart means to treat the spleen. Spleen is a son of the heart, treatment of spleen will deplete heart and supplement Lung. Excess of the lung will put under control excess of liver, which excess will stop control over the spleen, mother of the lung, so deficiency of the lung will be supplemented. This example was already presented in difficulty 81.
Difficulty 75 gives additional step to treat deficiency of the lung and excess of the liver. Additional step is supplementing the kidney. Lung is the mother of kidney, treating the lung practitioner will supplement kidney. Strong kidney will get under control the heart which will stop it's depleting control over the lung. This additional treatment also supplement the lung and increase control of the lung over excess of liver. It is an example of treatment of deficiency of west and excess of east by depleting south and supplementing the north.
Practitioners of archaic acupuncture use this practice of moving disease into sheng cycle by controlling ko cycle which develops diseases as it also explained in difficulty 53 of NanJing