David, let me more or less endorse the previous posts, but make a contribution along slightly different lines for those with even less access to Chinese than I have. Basically, I want to delve a little bit into some of the layers of meaning that Louis mentioned. Most of what I cite below I have unearthed looking through dictionaries.
While practitioners of Taijiquan usually talk about Qi as if it can only mean “vital energy,” this is by no means the only way it is used in Chinese. One can completely reject the basis of Chinese medicine and Taijiquan theory and still have lots of use for the word “Qi.”
A major meaning in Chinese is still “vapor,” “gas,” or “air.” One common word for the air in a room is “kong-qi,” which literally means something like the “Qi of open space.” The expression “da-qi” can mean to “inflate” something, like a tire. It can be interpreted as “knocking air (into something).” There are multiple terms referring to naturally or artificially occurring “gas” that use the word “Qi,” such as “du-qi” (“poison gas”), “mei-qi” (“coal or natural gas”), and “qi-qiu” (a “balloon” or “gas ball”).
From “air,” it is a short leap to the unseen things that appear to move or affect air. The ordinary word for weather is “tian-qi,” which could be interpreted either as the “air of heaven or of the sky” or as the “vital force of heaven or of the sky.” The modern word chosen to translate “electricity” (“dian-qi”) can be interpreted as the “vital force of lightning.”
In addition to the uses of “Qi” to mean “air,” it also has other extended meanings that refer to ordinary phenomena. It is used in expressions that can be interpreted as “being out of breath (Qi).” To pant is “huan qi,” or to make one’s qi “pant.” “To blow a puff of air” is “chui yi kou qi” (“blow one mouth Qi”). It is also used in some expressions in the meaning of “scent,” such as “xiang-qi”, or the “Qi of perfume.” Again, these concrete meanings can easily merge into things that are more ethereal. “Wok Qi” is the flavor food has when it comes straight from the cooking pot. It dissipates once the food sits around for a while. Perhaps, “losing the flavor of the wok” might be the way to translate this.
Another ordinary meaning of “Qi” that I can cite is when it is used to refer to the “air,” “manner,” or “aura” people are said to display in certain situations (e.g., “guan-qi,” or “bureaucratic airs”). In English, we might say that someone has a noble “air” about him or her, without necessarily trying to refer to any phenomena outside of Western science. A meaning that is probably related to this one is when “Qi” is used to refer to “spirits” or “morale.” (E.g., “Yang2 qi4” literally means to “have the Qi raised” and can be translated as “to be in high spirits.” “Qi is used in this latter sense in the Yang Style Saber Formula.)
“Qi” can also refer to “anger,” presumably with associations similar to what “being steamed or steaming mad” has in English. Curiously, the Chinese word for “steam,” although pronounced identically to “Qi” and probably constituting the same spoken word, is written differently. The “rice” component in the character is replaced by an element that means “water.”
As Louis mentioned in his earlier post, it is not always easy to disentangle all these layers of meaning. An “abdomen filled with Qi” might simply refer to “a stomach bloated with gas,” but probably implies that the flow of vital energy has also gone awry. A “Qi-filled abdomen” can also refer to a practitioner that has filled him or herself with good Qi through long practice. Again, I think that even in this meaning, a physical manifestation would be expected.
We must also recall that the ancient Chinese had a different view of natural phenomena than we do and so would not have made the same linguistic distinctions we do. In other words, they may have seen the Qi in air, scents, breath, gas, etc. all as different aspects of the same basic thing. The adoption of modern scientific views would not necessarily change either this cultural outlook or the structure of the language. In a similar vein, I have knowledge of a culture that uses the word “medicine” indifferently to refer to “medications,” “pesticide,” “magical amulets,” and “poisons.” If one talks about “being in good spirits,” this does not mean that one necessarily believes in ghosts or the soul.
Let me close with an expression I recently ran across in my losing effort to improve my Chinese: “Cheng1 yao1 da3 qi4.” This phrase could be crudely interpreted as “Prop up the waist and hit the vapor.” If the meaning of this phrase strikes you as opaque, you have a good excuse. I have deliberately chosen technically correct, but poor translations for each of these words to further illustrate why nuance can be important to meaning and true understanding.
The phrase really translates loosely as “to bolster someone up.” I will explain it word my word, since each of the four words actually has relevance for Yang Style Taijiquan.
“Cheng1” means “to prop up or support.” It is the word Yang Zhenduo uses to refer to the “propping” action of the front leg against the thrusting or treading action (“deng”) of the back leg as one shifts the weight forward into a Bow Stance. In the phrase under discussion, this word is probably best translated as “support.”
“Yao1” is what we normally translate as “waist”; however, as I have posted previously, this word also applies to the region of the lower back. Here the image is of someone supporting another’s lower back to give postural strength.
The root meaning of “Da3” is to strike. It is the word used to refer to the “open hand strikes” used in Single Whip, Brush Knee, etc. (“tui1 da3” or “push(ing) strike”). This word, however, is very often bleached of meaning and is used in a tremendous number of expressions as a dummy verb to refer to almost any manual activity, from gather firewood to buying cooking oil. In the expression “da Taijiquan,” I think it means something like “do Taijiquan,” or what some translate as “play Taijiquan.” The reason why many translate this word as “play” is apparently because “da” would have this translation when it is used to describe what one does with basketballs, tennis rackets, playing cards, etc. In Chinese, one does not “play” basketball, but rather “strikes basketball.”
The word “qi” in the phrase under discussion could refer to “air.” In this case, the expression “da qi” would mean to “inflate,” as I mentioned above. The implication would that one is “re-inflating” someone who has become “deflated” in spirit. I believe this instance of “qi” could also refer to “vital energy,” in which case “da qi” could be interpreted as meaning “to give or restore vital energy.” The best interpretation, however, is probably to construe “qi” as referring to “spirits” or “morale,” with the other meanings providing background “color.” “Da qi” would then mean to “lift someone’s spirits.”
With these clarifications, I could now translate “cheng1 yao1 da3 qi4” in a different, but still literal fashion as something like “support [someone’s] back and strike some spirit” into him or her.
As for “qi chen dan tian” or “sink(ing) the Qi to the Dantian,” this is about the only overt “manipulation” of Qi that the Yangs talk about. I think that because of the influence of other styles of Taijiquan or of Qi Gong, some Yang Stylists become enamored of esoteric or sophisticated practices to “feel” or manipulate Qi. For Yang Style, I think this unnecessary, because we all have felt Qi to the extent necessary.
When we slip and first feel our loss of balance, we feel our “heart” rise to our throat and our center of gravity rise. We have trouble breathing as our “breath” or “Qi” seems to feel caught or squeezed in our chest and throat. Our mind focuses on this point and leaves us feeling “tippy” or “top heavy” as we fear or sense an imminent fall. This, as I understand it, is what is meant by the expression “allowing the Qi to rise or to float.” “Sinking the Qi” is merely the opposite of this feeling. We feel for the stable connections that run through our bodies from our upper body to the earth, regardless of the arrangement of our limbs. We can attempt to do this even in the middle of losing our balance.
As we lose our balance, we have three ways to react. We can ignore the reality of the situation and continue to pour energy into a configuration that is changing catastrophically. This is usually the worst thing to do. Nonetheless, it is usually the originally source of our problem. The earlier we identify that we are pouring energy into a bad situation and that our movements are not based on a correct view of reality, the more options we have to change.
The second response is to panic as we perceive that reality is not to our liking. We go rigid. We allow our arms to flail around in a vain attempt to restore an equilibrium that is no longer obtainable in that manner. Time appears to freeze in an unfavorable configuration.
The third response is to try to sharpen our feel for the situation as it is, to change what can be changed, and to let go of the rest. You do not grope for traction that cannot be recovered, but feel instead for the actual state of one’s connection with the ground and what power can still be threaded through the body. If you can still separate full from empty to even a small degree, you are not irretrievable stuck. Even limited traction can provide enough leverage to improve the position of our bodies. Even when no traction is available, the mass of our bodies can still be useful as a source of root to accomplish some movement. This is what a cat does to right itself in mid-air.
Some styles of Taijiquan and some other martial arts do teach strong manipulation of “Qi.” Such practices may be beneficial with the proper teaching and training, but I do not believe they are integral to traditional Yang Style for two reasons.
The Yangs often state that their style is richly detailed, but nonetheless essentially simple. In seminars, they have often distinguished aspects of their practice from other those of other arts on the grounds that Yang Style keeps things simple and straightforward. Complicated breathing patterns or visualizations are thus contrary to the flavor of the form they cultivate.
Another reason why focusing on Qi is discouraged is because the idea in Yang Style is to allow Qi to flow naturally, not to control it arbitrarily. Just as one does not train to control the rate of one’s pulse, one does not train to control one’s Qi flow. The body knows what to do by itself. You merely need to train to get out of its way. As long as you use your mind correctly, the Qi will take care of itself.