The faintest touch; fragility.
Could you feel the wings fluttering through your fingertips? Could you feel the tiny but fervently beating heart?
“Listening” is a skill.
Ting Jin is often used to suggest Listening in a physical/kinetic manner.
True skill in TaiChi depends, at least in part, on cultivating TingJin. When we can “hear” what is being “said” we can take correct action.
This is the purpose of Sensing-Hands or Tui Shou excercises. Not to develop our own action (the form exists for that) but to practice Listening, to utilize TingJin.