"That’s what haragei’s for." The President slapped his own belly. "This is your center of gravity, your center of torque. You meet some enemy in free-fall, and you grapple with him, well, your head is just a stalk , see? What happens depends on your center of mass. Your haragei. Your actions, the places where you can punch out with hands and feet, form a sphere. And that sphere is centered on your belly. You think of that bubble around you all the time."