In the latest issue of Buddhadharma, Zen Master Harada Roshi was asked about the concept of Qi (ki in Japanese). He states that one can cultivate Qi doing yoga, qigong and tai chi, but that the best way is through meditation. Specifically discussing zazen meditation, he mentions that we develop Qi by “physically experiencing our essential oneness with the very existence of the universe,” and that the most important thing is that we “partake of [Qi] in its universal expression.”
There are numerous definitions of Qi, ranging from “energy”, to “matter on the verge of becoming energy/energy on the verge of becoming matter”, to “life-force,” etc. None of these really give the flavor of what exactly Qi is. Daoist priest and Chinese medicine expert, Jeffrey Yuen describes Qi as essentially the relationship between things. Qi, as a catalyzing force, cannot exist by itself. It only exists or serves a function between things.
I see this idea consistent with Master Roshi’s description above. The ability to “experience oneself not as a separate, limited body but as a body of the entire universe” to a large degree depends on the purity of the relationship, mediated by the purity of one’s Qi. Experiencing this oneness is akin to purifying our obscurations and realizing our buddhanature. During this process, while meditating, one calms the body, the breath and the mind and allows Qi to fill and permeate our being, overflow and eventually connect with and expand into our surroundings and eventually the entire universe.
Having this direct relationship with our bodies, environment and universe is the process of cultivation. In order to move beyond our own ego and self, one must cultivate and purify one’s own Qi.