上 工 中 工 之 治 病 treatment of diseases by highest and mediocre doctors

77th difficulty explains that when liver is in excess, it should not be treated, disease will move through ko connection to the spleen. This difficulty is linked to the treatment explained in difficulty 69. Excess should be treated through the heart meridian. It is explained in difficulty 53, when disease moves through shen cycle instead of ko. In this case heart is a son for the liver, puncturing the heart will deplete excess of liver, it's disease. Heart is a mother of spleen, puncturing the heart will supplement the spleen. Difficulty 69 explains this treatment
虛 者 補 其 母 ， emptiness should be supplemented by mother
實 者 瀉 其 子， excess should be depleted by son
當 先 補 乏 ，first treat repleting deficient 
然 後 瀉 之 。 afterwards treat depleting excess
In our case of liver excess disease will move to spleen, when spleen will become deficient. Treating the heart we fulfill emptiness of the spleen and deplete excess of liver. Heart is a meridian without excess or deficiency
不 虛  if there is no deficiency
不 實 ，neither excess
以 經 取 之 者 ， so this one meridian should be used
是 正 經   used the meridian
自 生 病 ， since diseases started
不 中 他 邪 也 ， not evil will come from  other place
當 自 取 其 經 ， treat same chosen meridian
故 言 以 經 取 之 。it is why they say treat same meridian
​Practitioner of archaic acupuncture treats pulse as it is said in difficulty 48, preventing disease from movement in ko cycles, moving it through shen cycle. Pulse is the principal guidance for archaic acupuncture treatment and prevention ​