In order to understand the movements and techniques of Hapkido, one must study and practice the theories of Yoo (flowing, as in water), Won (circle theory) and Hwa (non-resistance or harmony).

THEORY OF YOO (flowing, as in water):

Softness, adaptablility, strength, patience, conformity - all ideas which are present in the Eastern mind, and indeed in the mind of the Hapkido practitioner when thinking of the theory of Yoo. Water never struggles with any object that it encounters! It exhibits tremendous patience and adaptablility in it's engagement with any obstacle it faces during the natural 'downhill flow'. Rather than rising in direct conflict with an adversary, the Hapkido student seeks to join with, or adapt to the opponent and their motions, in order that the 'clashing' so commonly seen in many martial arts, is avoided. Although this is a demonstration of a keen ability to adapt, it is important to realize water never changes itself. The Hapkido practitioner must learn to adapt in this way. If a stream comes upon a rock in its downhill flow, it merely goes around it. If this rock is too large for the water to go around, the water will be patient, collecting until it rises to a level which allows it to flow over or around this obstruction. Similarly, as we "go with the flow" in the execution of our techniques, when we are pushed, we pull; when we are pulled, we push. In comparing an opponents defenses to an obstacle, a rock for instance, it should be noted that although the water can simply flow over or around the obstruction, it also eventually permeates every pore and completely engulfs the obstacle. This type of counter-attacking 'mind-set' is practiced in Hapkido through the very nature of the techniques and combinations which we train with every day.

Softness is another characteristic of water that relates to the understanding of Hapkido. We must accept the fact that softness has the capacity to win over hardness. It has been said that, "stiff and unbending is the disciple of death, while soft and yielding is the disciple of life." If you think of a Willow tree; during life, it's branches are flexible and resilient; but after death, they become hard and brittle. When thinking of water, however, it may be made to break up, but invariably, it will join together again.

Water has no shape. If you put it into a box, it becomes square; put it in a circle, it becomes round; freeze it, it becomes solid. Although constantly adapting to its environment, water remains basically unchanged. As for water's forcefulness, one need only observe a high water fall to be reminded of the force behind this very same soft and adaptable, yet forceful liquid.

A Hapkido principle that concerns a maximum use of force at one time can be easily explained when compared to the flow of water out of something like a fire hose, for example. One person can easily remove the hose from a fire truck; in this instance, it is light and flexible. However, when it's connected to a hydrant and water is forced through it, this same hose becomes very heavy and rigid. It now demands three people to handle it due to the concentration of water at one point beyond the nozzle of the hose. Hapkido compares a persons 'Ki' power to the water in a fire hose. You should be able to concentrate all of your power in one direction toward one point.

THEORY OF WON (circle):

A circle represents the perfect geometric figure. Every person has his or her own circle that is their "private space." It is this circle that we seek to protect. An opponent's attack should be met with a graceful, circular defensive motion. We choose not to meet an opponent's force with direct force. Instead, we choose to lead this oncoming force in a circle, deflecting it, so as to minimize its effect. Therefore, we end up redirecting an opponents force against himself. We should think of this circle as a form of least resistance; always moving (active), and therefore difficult to hold or grasp.

Because the student of Hapkido chooses to deflect an attack in a circular manner, he/she gains an immediate advantage in several ways. First, injuries are less likely to the defender when the attack is not met squarely. Second, the defender sets up the opponent for a powerful, nearly unavoidable, counter-attack. Third, the opponents balance, the very thing he needs most, is destroyed. And lastly, the opponents body position is controlled so as to afford the defender the option of a much more devastating, continuous, circular combination of counter-techniques. During joint manipulations, the circle theory is applied by bluffing the attacker into a motion that is overcome by the defenders counter-circular force.

THEORY OF HWA (harmony or non-resistance):

The learning of Hapkido is accomplished through the continuous generation of harmony between mind, body, techniques, and environment. Harmony is the most important element one should strive to achieve through their training. How often in your training do you feel that your mind has "learned" a new technique, only to find that your body is not embracing this new knowledge as rapidly as you desire? Each time we perform a technique, connections are made between the brain and the muscles which control the movements of the technique. Every maneuver you learn through Hapkido training has it's own special 'control center' inside the brain. We practice what we are shown countless times so that our body and mind will eventually act as one unit in response to a confrontation.

After one achieves harmony within himself, the next requirement is to harmonize with one's opponent. Having accomplishing this, the Hapkido student will find it quite easy to control the movements and energy of an opponent. We seek to blend or harmonize with the attack to create the defense. The words "non-resistance" are often substituted for harmony in defining the theory of Hwa. Before an attack can be directed in a circular manner, it must first be received or intercepted with a non-direct block or maneuver, thus allowing a harmony to be created using the opponents oncoming force to fuel the defending motion.

Following this, learning to harmonize with one's environment is the next stage. The final task is blending the harmony that one has developed with himself, his opponent, and the environment, with that of the techniques.