Pushing hands is said to be the gateway for students to experientially understand the martial aspects of the internal martial arts (內家 nèijiā): leverage, reflex, sensitivity, timing, coordination and positioning. Pushing hands works to undo a person's natural instinct to resist force with force, teaching the body to yield to force and redirect it. Some t'ai chi schools teach push hands to complement the physical conditioning of performing solo routines. Push hands allows students to learn how to respond to external stimuli using techniques from their forms practice. Among other things, training with a partner allows a student to develop ting jing (listening power), the sensitivity to feel the direction and strength of a partner's intention. In that sense pushing hands is a contract between students to train in the defensive and offensive movement principles of their martial art: learning to generate, coordinate and deliver power to another and also how to effectively neutralize incoming forces in a safe environment.