To injure an opponent is to injure yourself. To control aggression without inflicting injury is Aikido.    
It is necessary to develop a strategy that utilizes all the physical conditions and elements that are directly at hand. The best strategy relies upon an unlimited set of responses.  A good stance and posture reflect a proper state of mind. 


The key to good technique is to keep your hands, feet, and hips straight and centered. If you are centered, you can move freely. The physical center is your belly; if your mind is set there as well, you are assured of victory in any endeavor.           

"Morihei Ueshiba"