《黄帝内经·灵枢·刺节真邪》
如果某一经脉上实下虚而不通畅，这一定是横络受邪，并且邪气势盛，因而影响到正经，使它不能通畅。
一经上实下虚而不通者，此必有横络盛加于大经，令之不通，视而泻之。
If a certain meridian is stuck and empty and not smooth, it must be that the cross-collaterals have been affected by evil, and the qi of evil is strong, which affects the regular meridian and prevents it from being smooth.