通于九变 (通於九變) tōng yú jiǔ biàn

tōng yú jiǔ biàn phrase to thoroughly understand the nine variations [of tactics]
Domain: Literary Chinese 文言文
Notes: Quote: from the Warring States period text 孫子兵法 “Art of War” by Sunzi, section 8 (Amies 2021 tr.; see also tr. by Giles 1910, p. 74)