Originally Posted by
taai gihk yahn
"qi" is a metaphor, albeit one that encompasses a variety of phenomena;
the character for "qi" was originally a pictogram depicting vapor rising off of fermenting rise; as such, the concept was firmly grounded in observable phenomenon; in TCM it generally correlates with a variety of relatively objective physiological processes that are clearly described and understood using contemporary knowledge paradigms; it was / is utilized to describe those physiological functions that were at one point observable only at a macro level; in some cases it was a discreet function that we would recognize today, such as respiration; in other cases, it was the net function of what we would refer to as a physiological system, such as digestion; in other cases, it referred to what would at present be defined as relating to a psychological state, be it a primary organic (e.g. - schizophrenia) or environment based (e.e.g - PTSD); of course, "ancient" Chinese culture included ideas about spirits, demons, etc., as well as a variety of other fantastical stories, so"qi" got tied up into some of this stuff as well, such as Taoist Immortals riding around on purple clouds...
the idea of "rhythm" permeates the metaphor of "qi": that is, a fundamental concept is periodicity, which is part of what gives the construct a great deal of predictive and prognostic power in context of medicine: basically by observing various rhythms in the body, one can become adept at correlating changes in one rhythm with another
"qi" also is used to describe a variety of relatively subjective sensorial experiences, such as what one might experience during certain types of exercises that impact the sensorimotor system; these include meditation, qigong, taiji, etc.; like any other form of exercise, these practices impact the physiology in different ways; if one ones 5 miles, the physiology will change to reflect that sort of activity, and one will experience an internal state change (e.g. - "runner's high"); likewise, if one practices "100 Days Opening", one will also have a set of "internal" experiences that reflect the nature of that particular practice; specifically, one will experience changes in one's autonomic nervous system that will cause various sensations internally, such as heat, feelings of lightness or heaviness, euphoria, calmness, etc.;
the idea of looking for "qi" as a discreet entity, as some sort of energy akin to heat, gravity, electricity, magnetism, potential / kinetic energy etc. is a fallacy; that's because the processes that "qi" describes all contain these energies to a varying extent: if we talk about the function of the human body, any time you describe any physiological process, you involves all of these forces; "qi" is a the unifying descriptor; that includes emotional / psychological function as well;
saying that "qi" cannot be described by / doesn't need "science" is an extremely narrow-minded perspective; the bod is the body; the universe is the universe; different people / cultures have described it in different ways, but we are all looking at the same thing; the difference is one o approach: so-called "eastern" culture, to some extent, looks at the macro in order to understand the micro (relatively speaking); so-called "western" culture looks at things in a reductionist way, trying to understand things at their "smallest" in order to then understand the whole; meaning, that, both are "holistic", just coming at it differently; I find it interesting how people are so quick to point out the "limitations" of science, and talk about how the Chinese really understood the "internal" workings of things so much better: well, the Chinese didn't know about cellular function, DNA, atomic theory, sub-atomic particles, etc.; certainly, their perspective might have inferred it, but if anything, current "science" has looked at the "internal" much more deeply than any one else has done, ever; strange then, that this "mysterious energy" manages to evade objective detection, but exists very abundantly from a subjective perspective, usually amongst people who do not posses the knowledge to correlate what they feel with current understanding of physiology...
"qi" was what was used when the technological limitations got in the way of specific observation at a level smaller than what was observable with the human senses at the time; it described a gestalt effect with the main purpose of having predictive / prognostic value in medicine, but also as a means of talking about the interrelated nature of all things, something that has been a commonly discussed idea throughout the history of mankind, but every different culture, in lots of different ways; so nothing unique there - it's all in context of how we as humans experience the universe within which we "exist"