Taekwon-Do Study Companion is about promoting thinking in Martial Arts. There are practitioners that do not really think about what they are doing. They just go on and do it anyway, without too much thinking and without actually caring whether it is correct or not. Although this may be acceptable for 5 year olds, it may not be wise, when referring to the essence of a Martial Art. Therefore, this volume is not addressed to them. Taekwon-Do Study Companion is addressed to those, who not only accept the fact that Taekwon-Do “is the scientific use of the body in the method of self defence”, but are also willing to take the extra step, in order to fulfill this definition. It is crystal clear that you cannot have science without study. This kind of science has not been invented yet. What area of expertise is most useful when studying Martial Arts? Physics may be useful, as the Founder of Taekwon-Do implied, repeatedly using common equations for explaining his Theory of Power. Mathematics is probably the purest and most universal form of science and one that does not need translation. A particular branch of Maths, Geometry may be extremely useful, particularly Trigonometry. Medicine, when properly viewed as the exact science about optimal human body function, may have alarmingly common features with serious Martial Arts study. Oriental Medicine in particular has infinite applications, using points in the body with special properties, discovered through ages of practice and study. These points, regardless of their name, may be used in manipulating function, exclusively for healing purposes in Medicine, but with somehow more options in Martial Arts. Effective use of these points requires endless hours of study, in order to master their use. Afterwards, comes the problem of choosing how to use them. Naturally, with choice comes responsibility and that is exactly where Philosophy comes in handy. Obviously, no single area of knowledge may adequately prepare the practitioner for applying Science in Martial Arts. However, scientific methodology is mandatory in Taekwon-Do, in order to appreciate correct body posture and function. Practitioners who realize this simple truth, practitioners who love science and/in Martial Arts, scholar Martial Artists, are the target group of this volume. These scholar Martial Artists, regardless of age, grade, degree, professional or academic background, consider themselves eternal students. Therefore, a student companion to the Encyclopedia should be extremely helfpul. The authors do not claim to provide definitive answers, but rather stimuli for further thought or, at times, a different point of view, possibly an innovative perspective.