There are several fundamental lines that we use to help visualize concepts and communicate movements, directions, and ideas. Below are the primary lines and planes with which you will want to be familiar.
Before we begin let’s review some very basic geometry. A line is a direct connection between two points. A line is often described as the shortest distance between two points. While this may not always be true, it is generally true when working with everyday things and will serve fine as our definition for a line.
A plane is a flat surface that has both length and width (or more accurately, that has an x and a y-direction). A flat wall in your home can represent a plane. The entire surface of the wall might be thought of as a single plane. The glass in a window is another common example of a plane. It is flat and expands in two different directions from its center. In geometry, a plane is generally considered to have no depth at all. It is just a representation of the surface of a flat object, not the entire object. So while the surface of a sheet of glass is a plane, the entire sheet is too thick to be a single plane. The front and back surfaces of the glass would represent two different (but parallel) planes.
Now let’s discuss a few lines that we use frequently when discussing movement or interactions with others.
The Mother Line is an imaginary line that extends from the top of your head down through the exact center of your body, eventually exiting down through your groin. If you are bent forward, to the side, or backward then this line is bent or broken. You want to keep this line as straight as possible when performing martial activities, though there will be times when it will be advantageous to bend this line (for example, if you are kneeling).
The Center Line is another imaginary line. This time it starts at your Mother Line near the center of your chest area and extends out directly in front of you. This is, in essence, where you are pointing and is the direction in which you would move if you step directly forward. This line forms a right angle with your Mother Line. Therefore if you lean forward your Center Line will dip down. The Center Line extends directly from your Mother Line and out through the tip of your center triangle. If you rotate about your Mother Line, your Center Line will swing to the left or right.
The Central Line has less to do with your body than do the Mother Line and Center Line. The Central Line is a line directly between your Mother Line and your opponent’s Mother Line. This often defines the line along which you would wish to hit to strike directly to the opponent’s Mother Line.
The Center Plane is a plane that intersects your center line and your mother line. It originates along your mother line and extends outward directly above and below your Center Line. If your Center Line moves, the Center Plane moves with it. You will often want to ensure that your Center Plane is aligned directly along the Central Line. In other words, you will want to have your Center Line pointed at your opponent’s Mother Line, especially if you are prepared to strike your opponent. This is not always required or useful, but it provides a simple model you might employ when you consider striking someone.
The Central Plane is a plane that is formed by all possible Central Lines between you and another person. It is the plane that intersects your Central Line and the Central Line of your opponent.
When you are moving relative to your opponent it is often useful to think about ensuring your Center Plane is aligned with the Central Plane. This ensures that as you and the opponent move you will remain focused and centered on the opponent. This is not always necessary, but it provides an excellent first model for how to remain focused and centered on an opponent when the two of you are in constant motion.