One way to test whether the practitioner knows how to fa Jin is as follows: a. Have a sand bag loaded full of sand, b. Ask him to fa Jin onto the sand bag with his two palms i.e an, as in peng li chi an, c. You hold the sand bag softly but firmly as in ding Jin,use both hands. Your purpose is to feel the movement of the sand. Of course away from the direction of his Jin. But if you are good at your Taiji, you can hold directly at the opposite side. d. As he fa Jin,feel the movement of the sand in the sand bag : If you detect no movement of the sand inside, he has a loud mouth, If the whole sand bag moves but not the sand inside, he pushes, If you detect slight movement of the sand only around where he pushes, that is brute force not fa Jin, If you feel a sudden upheaval of sand movement in the bag but the sand bag hardly moved, that is fa Jin, If you are holding the sand bag opposite the fa Jin, you will fill a sudden rush of force towards you, if your hands are stiff you are going to get hurt ...........