Man is by necessity born with his mind and body on earth, and it is impossible to maintain one's mind and body in harmony unless one relies on the principle that has existed since before human existence. This principle, according to which everyone can control his own mind and body and live his life, has been called "TAEKWONDO"⁶⁾ by senior masters. There are ways in which the planets move through the sky, ways in which birds and beasts travel along the earth, and also rules that mankind should obey in society. Likewise, there is also a right way by which we should control our hands and feet whenever we make a motion. This is another aspect of TAEKWONDO. Man's life can be constructed only by his own motions, and such motion contains within it everything of him, including inherent nature. Owing to these reasons, we may term Taekwondo a Do ([]), which contains the eternal principle.

Do is what makes everything such, i.e., it is the principle that penetrates all things. The very principle that imbues and penetrates and constitutes the natural "suchness" of all things is called Do. It transcends every distinction and discrimination. So there is neither a part nor a whole in it. Because it has neither part nor whole, to know it is to know everything. Therefore, every single word written here is not a piece of knowledge on TAEKWONDO. It is an entirety of itself that includes everything.

Since early times many men and women, relying on what each of them had attained, have divided TAEKWONDO into three aspects; i.e. Musool (martial technique), Muyae (martial art), and Mudo (martial principle). Musool (martial technique) refers to those techniques with which you can control and conquer your opponent. Muyae (Martial art) is the method of obtaining harmony of mind and body with which you use the martial techniques at the level of art, sublimating distinctions between mind and body into perfect harmony. Mudo (Martial principle) refers to the comprehension of the ultimate truth beyond the more practical level of Muyae. All of these distinctions among Musool, Muyae and Mudo, however, will and must disappear in the end. Thus, talking about Taekwondo, as merely Mudo will hide its true Do. Things people distinguish look as different from one another as if such distinctions were real. What is real, however, is the existence of the entirety of everything mixed in changes with one another. Therefore, Do reveals itself in the simple practice of Taekwondo. Therefore, everyone should know that even the truth of the words you read here are not in the book but rather in the right motions of those who perform Taekwondo.

Do () exists in reality. However, since it transcends every distinction though you may grasp it you cannot explain it. Therefore, there is no one who can talk about Taekwondo only as Mudo (martial principle). For this very reason ancient masters referred to it only as "Muyae" (martial art) but not "Mudo" (martial principle), even though such a profound martial principle has not been kept alive and vibrant for several thousand years now. It is to instruct people in a direct way the meaning concealed behind words that I employ the word "Mudo" (martial principle). But Taekwondo must be understood as the total Oneness of Musool (martial technique), Muyae (martial art), and Mudo (martial principle), in the past as in the present. Do is inherent in every aspect of Taekwondo.