The Six Harmonies of internal martial arts refer to the harmonizing or coordination between three of the bodies joints (6 total) and the coordination of three internal harmonies.
External Harmonies
1) The hands harmonize with the feet.
2) The hips harmonize with the shoulders.
3) The elbows harmonize with the knees.
Internal Harmonies
1) The emotions harmonize with the intention.
2) The intention harmonizes with the chi.
3) The chi harmonizes with the power.
“Coordination” or “harmonizing” the external harmonies includes good posture and the body parts moving in unison. It does not necessarily mean you are moving like a robot or that your limbs aren’t moving in different directions at times. There's much more to it.
One simple example could be your hand moving towards your opponent's centerline and your foot pointing in that same direction. Another example is beginning a movement in your knee at the same time you begin a movement in your elbow. In Wing Chun, we think of the knees and elbows driving the movement. Yet another example is when your hand places pressure on your opponent your foot should also place pressure into the ground. We call this having an associated foot.
You should prioritize your development of these harmonies. First you should work to unify the external harmonies of the hips and shoulders. At the same time, you are working to harmonize the emotions with your intention.
Posted by Adam Williss, Founder of The Dragon Institute