There are three primary principles in Hapkido. The first is Yu, the theory of flowing water. You should never meet the force head on. Instead, you should divert the flow of the attack with softness and disperse it. The secondly theory is Won, the theory of the circle. Circular movements make it possible to use the attacker’s force against them. The last principle is Wha, the theory of harmony. The ability to harmonize with the opponents force and make that force your own.