TL;DR – Box Theory and the Five Limbs Your torso is a box. The corners are your left shoulder, right shoulder, left hip and right hip. The spine runs through the middle as the axis and the head is the steering wheel on top. Out of this box stick five “limbs”: two arms, two legs and the head/neck. Grappling is just learning to fix, wedge or lever the box while isolating one of those limbs. Neutralise the box, then attack a limb. That’s the whole game. The Little Box On Your Torso Most people first meet jiu-jitsu as a tour of positions: guard, half guard, side control, mount, back, submission. That’s useful, but underneath all of those positions there’s something simpler running the show. Every fight is two boxes trying to bully each other. In our language the torso is “the box.” The four corners of the box are the shoulders and the hips. The spine runs down the middle as an axis. The head sits on top like a steering wheel. If that box can move freely, turn where it wants and sit on good base, you are still in the fight. If the box gets pinned, twisted or folded, life becomes very bad very quickly. So the fundamental goal underneath all techniques is the same: fix, wedge or lever the corners of the box so the other person can’t move in a useful way. The Five Limbs Escaping The Box Now imagine that box drawn on the torso. Out of it poke five limbs. One arm escapes out of the front left corner, another out of the front right corner. One leg sticks out of the bottom left corner, one out of the bottom right corner. And then, rudely, the head and neck stick right out of the top like an extra limb that thinks it’s in charge of everything. Those five limbs are how we both survive and attack. The arms frame, post, grip and underhook. The legs step, post, hook, elevate and create all our guard work and leg entanglements. The head drives posture, balance, direction and access to chokes. The head gets special status. Wherever the head goes, the spine follows; wherever the spine turns, the whole box rotates. If I snap your head down, your posture disappears. If I turn your head, your back starts to show. If I pin your head, your bridges and turns die. For that reason we treat the head and neck as a “fifth limb” sticking out the top of the box.