Restraint takes place with the torso, which means that this one applies restraint to his own body. This one himself applies restraint to his body [i.e., knows when to stop and does so]
Wang Bi’s commentary establishes Restraint (Gen) as a somatic and ethical principle: properly placed self-restraint at the body’s median zone constitutes virtue, while misplaced restraint splits the whole and produces catastrophe.
, The Classic of Changes: A New Translation of the I Ching as Interpreted by Wang Bi, 1994thesis