"Apart from its unrivalled value as a method of self-defence. Judo as a sport possesses qualities not easily surpassed by any other. Its theories are quite simple, yet the practical methods of their application, numerous in number according to the ever-changing postures of the human body, are by no means as easy as at first sight they may seem, and it is this fact which invests the practice and study of Judo with endless variety and interest. The vital factors in Judo its perfect balance, both physical and mental, lighting speed of movement and judgment of time, mere strength is not greatly relied on. Nevertheless, the physical energy involved in the practice of judo is universal and develops muscles supple and quick in action."

Principle of Judo is Like the Nature of Water

G. Koizumi, "Father of British Judo", 1925