Wing Chun is a highly logical and sensible Gung Fu system that was scientifically designed for and based on human body motions. Ng Mui and Yim Wing Chun built the ultra-effective and economic system of close-range combat practiced today based on geometry, physics, physiology, and philosophy. Complex concepts and principles govern how skilled fighter instinctively applies their techniques. But, of all the ideas and principles that distinguish the system, one is so fundamental to Wing Chun’s fighting strategy that it can be referred to as the “Backbone of the System.”

This “idea,” known as the “Centerline Theory” (Joong Seen Lay), entails recognizing, using, and manipulating an imaginary line or plane that connects two fighters, as well as the relationship of that line or aircraft to various bars and angles of attack and defense. Because the Centerline Theory is based on geometry, two fighters’ motions and postures are referred to as lines, triangles, planes, pyramids, and angles rather than stances, punches, and kicks. As a result, the Wing Chun student must be able to visualize them as such, effectively “depersonalizing” the opponent, himself, and the blocking and attacking motions used by both during combat, allowing all elements to be viewed clinically. This ability is developed through many hours of intense practice on Sticky Hands, sparring, and drills, all of which accustom the student to dealing with relentless attack pressure while remaining calm under fire. While the student may initially flinch or panic when attacked, he will soon begin to view oncoming kicks and punches as routine everyday occurrences, more like “fodder” for technique practice than a severe threat.

At this point, the student can see the lines, angles, and pyramids formed by both fighters and the implications for his structure. This emotional detachment enables him to apply the Centerline Theory. To eliminate the adverse effects of tension, fear, or anger, which can impede the effective use of the Centerline strategy, the Wing Chun fighter must learn to remain calm and relax the mind, even amid all-out combat.

Although the Centerline Theory may appear complex and even a little too confusing to apply in a real-world combat situation at first, the Wing Chun student will discover that once the core concept is grasped, using the Centerline strategy becomes more and more natural. In other words, without consciously thinking about it, the student will begin to apply the Centerline Theory instinctively in conjunction with all other key concepts and principles of the system. Before delving into the Centerline Theory, the major components of its operation must be identified and defined. Once these elements are fully comprehended, the reader can see how they interact to form arguably the most scientific and efficient approach to unarmed combat. The “Motherline,” “Self-Centerline,” “Centerline Plane,” “Attack and Defense Pyramids,” and “Centerline Advantage” (also known as “Inside Centerline”) are the major components of the Centerline Theory, as is the concept of the Giu Sau Error. The following is a detailed examination of each.

The “Motherline”—In Chinese, the Jick Joong Seen or Jick Seen is an imaginary vertical line that passes through the middle/top of the head and down through the center of the body to the floor, forming an axis of rotation for the body. The Motherline does not change when a person pivots on their axis. However, if the person moves in any direction, the Motherline shifts accordingly. The Motherline, as opposed to the Centerline, is a Surface feature that runs through the center of the body. If you consider the body a cylinder and Spin it, the Centerline will, of course, move. The Motherline would not because that is what the Centerline would be doing.

The “Self-Centerline”—The Self-Centerline, is the vertical line that divides the body into two halves. When there is no opponent, the SelfCenterline runs down the head and body’s middle/front and back like a painted-on stripe. It can be used as a reference point for correct elbow and hand position during technique execution during forms practice. Specific block structures require that the elbow, wrist, or another part of the hand be on the Self-Centerline. In contrast, specific attack structures need the knuckles, palm heel, elbow point, or other areas to be central. When performing the Tan Sau motion in Siu Leem Tau, for example, the middle finger should point 45° inward toward the SelfCenterline from the origin of the action until it reaches that line and continues to follow it as the elbow is drawn in so that both the middle finger and the inner elbow end up on the SelfCenterline in the fully extended Tan Sau position.

In reality, the Self-Centerline arises from the Motherline and radiates outward from the axis of the body. When an opponent is present, the SelfCenterline is used as a reference point in the construction of Attack and Defense Pyramids and a primary target area. Most of the vital issues of the body fall somewhere on this line, front or back, so the Wing Chun fighter will usually focus his attack power on it. If you were to shoot an arrow into your opponent while aiming at the Self-Centerline, your attack would undoubtedly be more damaging than if the arrow penetrated any part of the body that was not on that line. Unless it were aimed at the Motherline from the outside and penetrated far enough to reach the vital organs the long way, the arrow would most likely not pass through any essential organ.

This is why the Self-Centerline must be carefully defended and why it is the primary target of the Wing Chun attack. Furthermore, when a punch lands off the Self-Centerline, the opponent can roll with the force of the blow using the Motherline as the pivotal point, effectively dissolving most of its impact. In contrast, a solid blow to a point on the Self-Centerline will be fully absorbed by the opponent because the pivotal moment is negated by the central focus of the punching power, leaving him no opportunity to “roll with the punch.”

Centerline Advantage—To defend against a hand attack in the proper Wing Chun manner—that is, by using Angle Structure to overcome greater force—the student must instinctively combine some aspects of the Centerline Theory and apply them instinctively with proper technique, power, and timing in one smooth motion supported by the appropriate footwork to create optimum Centerline Advantage. For example, when an opponent launches a punch that the Wing Chun fighter perceives as a horizontal pyramid, the Wing Chun fighter quickly and instinctively “sizes up” the situation and recognizes the punch’s pyramid structure. He processes that information while projecting the Defense Pyramid he believes is most appropriate for the position. Because the Wing Chun practitioner is always aware of the Centerline, he already knows where to direct his defense hand’s energy: to a point between the tip of the Attack Pyramid and the Centerline. By doing so, he combines the concept of the deflective reaction of two colliding pyramids with awareness of the Centerline Plane, which tells him which direction to guide that deflection.

The term “Centerline Advantage” is defined as having the tip of your Defense or Attack Pyramid between the end of your opponent’s pyramid and the Centerline. To defeat an attack structurally, the defender must wedge the tip of the appropriate Defense Pyramid between two points: the end of the opponent’s Attack Pyramid and the Centerline. This method requires the least amount of muscular strength, relying instead on the Cutting Angle and deflective power of the pyramid to achieve the winning position geometrically. Whoever can get the tip of their Attack or Defense Pyramid between the appropriate coordinates wins. Suppose your pyramid is pointing down and in. In that case, it will point up and out, giving you Centerline Advantage if the tip of your pyramid also points down and in. This Centerline Advantage position is also known as “Inside Centerline.” However, it does not necessarily mean that the defender’s hand is inside the attacker’s hand, only that the defender “has the line”—that is, he has his hand between the opponent’s technique and the Centerline.

Changing the Line- Physically moving a mighty attack pyramid off the Centerline as quickly as in the Chee Don Sau example is not always possible. When an attack is so powerful that the Defense Pyramid cannot move it off the line, it is necessary to take other precautions to avoid being hit. Suppose the Attack Pyramid cannot be moved off the Centerline. In that case, the Centerline can quickly move away from the attack. Consider the Attack Pyramid and the Centerline, which must be manipulated in proper Wing Chun defense. Suppose the defense hand is placed on the attack hand but cannot move that hand away from the Centerline. In that case, the defender has the option of shifting the position of the Centerline itself rather than attempting to move the attack away from its intended path. All he has to do is change the endpoint of his side of the Centerline Plane by moving his own Motherline. He has moved to a position where his own Defense Pyramid now falls between the tip of the Attack Pyramid and the new line created by his stance movement, resulting in the same Inside Centerline relationship as if he had been able to move the Attack Pyramid off the line.

To summarize, if an attacker attempts to punch you in the nose and you cannot move the punch, move your nose! This can be accomplished by any Moving Stance that changes the line, thereby supporting the defense hand by improving Angle Structure, increasing power, and possibly improving the Angle of Facing. The important thing is that the line is moved in the right direction to gain Inside Centerline as quickly and cheaply as possible.