伤寒治法先要明表里虚实.能明此四字.则仲景三百九十七法.可坐而定也.何以言之.有表实.有表虚.有里实.有里虚.有表里俱实.有表里俱虚.予于表里虚实歌中.尝论其事矣.仲景麻黄汤类.为表实而设也.桂枝汤类.为表虚而设也.里实则承气之类.里虚则四逆理中之类是也.表里俱实.所谓阳盛阴虚.下之则愈也.表里俱虚.所谓阳虚阴盛.汗之则愈者也.尝读魏志华佗传.有府吏倪寻、李延共止.俱头痛身热.所苦正同.佗曰.寻当下之.延当发汗.或难其异.佗曰.寻外实.延内实.故治之宜殊.此所谓能明表里虚实者也.