You have now been formally introduced to the Four Pillars of Advanced Jujitsu Concepts.  Do these four pillars only apply to jujitsu?  No, they apply to all martial arts, regardless of system of style.   Techniques practiced without sound scientific principles of anatomical physics are only hollow techniques.  On the surface, they seem interesting to practice and demonstrate.  But at the core of reality, there is nothing substantial beneath the surface of the technique.  One who practices their arts in this fashion creates an illusion of reality.  Regardless of what one does in a class situation, the streets are real and the people that inhabit the streets are part of that ultimate reality. Never forget the Four Pillars of Advanced Jujitsu Concepts.