The subtlest is the most powerful. This is the power of the human spirit, the will to live, wisdom and compassion. One of the most important things I learned in Acupuncture School is the importance and power of a practitioner's intention. It bears repeating.
Subtle healing is powerful.
Your intention as a practitioner matters a great deal. Medical Qi Gong, or external Qi Gong, is little known in the West. It is a method of working directly with another person's Qi, as opposed to using acupuncture needles, herbs, or any other external tool. Internal Qi Gong as a form of self-healing, health maintenance, and martial art is a practice for laypeople to do themselves. There is much confusion in the West about use of terms and distinguishing between the two types, so these definitions are for the purpose of this article, and may be disputed elsewhere.