For should the enemy strengthen his van he will weaken his rear should he strengthen his rear he

“For should the enemy strengthen his van, he will weaken his rear; should he strengthen his rear, he will weaken his van; should he strengthen his left, he will weaken his right; should he strengthen his right, he will weaken his left. If he sends reinforcements everywhere, he will everywhere be weak.”

“The Art of War by Active 6th Century B.C. Sunzi.” Gutenberg.Org, https://www.gutenberg.org/ebooks/132. Accessed 16 July 2021, loc. 78.

This is, again, a restatement in different phraseology of the idea that vulnerabilities are not fixed (static), but can be revealed through the use of what Sun Tzu referred to as ch’i and cheng.