When an forward momentum is encountered the course it takes can be altered by slight pressure at specific angles, this creates a new axis point for the movement and if the angle and pressure is applied constantly this results in spiraling of the momentum via the control of a slighter secondary force.
With a forward momentum the angles that work are those that do not oppose the momentum, the first angle that becomes effective is at 45 degrees to the line of the momentum. This pressure to the momentum if maintained at a 45 degree or so, to the primary momentum, causes an arc or a spiral to form.
Perpendicular to the path of momentum is a potential field in the shape of the movement that will control the movement via secondary and slight forces to the initial force or momentum, this field starts and ends at the 45 degree line running through the center of the momentum. This allows variable angles to be used within the field in a successive manner while still in the ideal area and at the ideal angles for controlling the initial momentum and mass. The two successive pressures should be at about 90 degrees to each other, but neither more acute to the center axis of the initial momentum than 45 degrees. This results in an S shaped movement to form, instead of the arc or spiral caused by one pressure alone.
These angles and fields can be used with every energy of taiji.
Knowledge of them is of use only to those who practice.