Hapkido has many principles that are continually repeated during one’s training. These principles are meant to guide the student in physical, mental and spiritual improvement. All Hapkido practitioners soon learn that the study of Hapkido is more than just a set of combative techniques. Hapkido is meant to only be used for self-defense or protection of others. The physical ability to fight well is usually considered to be just a secondary gain to the process of personal development. There are three main philosophical principles from which most all other principles stem from. These principles are the theories of harmony, water, and circles.
The harmony theory states that one must tune the body, mind, and spirit in order to achieve perfect synchronization with one’s environment and society. The word Hapkido can be translated into “the art of coordinated power”. Once someone has learned to coordinate their mind, body, and spirit then everything they do is with purpose and is in turn linked to the moment of its existence. This is a common Taoist concept. To achieve this state one must empty the mind and obtain total awareness of everything around them. By doing this one will become one with their environment and will flow in harmony with its changes in state.
The water theory draws its ideas from the behavior of water. Water will always find the path of least resistance. When the path is obstructed with an obstacle it will apply constant pressure until the obstacle has been penetrated. If yet another obstacle is placed in the way it will adapt to this change and once again find its way. Water can be quite destructive to the obstacles in its way however its force requires little energy. Bruce Lee once said, "Empty your mind, be formless. Shapeless, like water. If you put water into a cup, it becomes the cup. You put water into a bottle and it becomes the bottle. You put it in a teapot it becomes the teapot. Now, water can flow or it can crash. Be water my friend."
The circle theory is based off the idea of a circular universe. Circles are found in many cultures as symbolizing important concepts such as wholeness, perfect unity, eternity, and time. In the ranking systems of Hapkido a student starts out as a white and works their way through colored belts first until they reach the black belt. From there they progress through the different levels of black belts until they reach the tenth level at which they become grandmasters and once again wear a white belts. Most of the movements in Hapkido are based on circles. It is often said that to move in circles is to move in harmony with your opponent, self and the universe. If you don’t do this then you are fighting your opponent, yourself and the universe every step of the way. As it turns out this circular movement provides for a certain unpredictability that prevents your opponent from countering your actions and allows you to gain more leverage and strength in your techniques.