Peace
Five Elements: Steal Step: Link
In Mandarin, you could express "I know everything about you, but you know nothing about me" as "我了解你的一切,但你对我一无所知" (Wǒ liǎojiě nǐ de yīqiè, dàn nǐ duì wǒ yīwúsuǒzhī).
To get to know your opponent, you must make specific contact. Your and your opponent's bodily centers must connect or link. This linkage will become useful once information about their body shape, energy, and reflexes has been gathered. However, the opponent is searching for the same as they try to determine your deficiencies.
Under these circumstances, footwork is important to test and mislead by telegraphing fake centers and attacks. This can be done through telltale facial expressions, switching intent in the hands and legs, or turning a false strike into a genuine one to evaluate the use of their linkages. Once a set or sets of weak links are discovered, attack them. Sifu Chen would say, "If a bucket has a whole in it, water flows through."
He employed the two-person set to demonstrate how to follow while investigating the opponent's weak links.