One of the most difficult and yet easiest to execute, this most important Chinese word with reference to Taijiquan will give you the exactly what the classics tell us that we should receive when practicing Taiji.
The problem that most people (well all actually) is that in the beginning we all TRY to 'sink' the Qi and as Qi is an abstract sort of thing that we generally cannot feel, it is impossible to make the Qi flow sink. In fact you cannot make the Qi flow do anything using your conscious mind. It's like trying to influence your blood flow by thinking about it, it is an automatic motor action within the body that cannot be influenced by conscious thought because it is so important. We were made this way in order for the body and its automatic functions to work properly without hindrance.
And it's the same with our Qi flow, only there are two reasons why we are unable to influence it using our conscious mind. The first is the same reason as for the blood in that our Qi is of course very important for good health as we would die without it and its flow. The 2nd is that if we were able to control our Qi, we would be able to damage others at every selfish or revengeful whim.
The trick to getting the Qi flow to do what you want it to (to SINK) lies hidden in a phrase that I always remember, told to me by one of my teachers way back.
In fact it was one of the very first things he told to me, thus:
"Qi is like a shy girl; she looks at you from behind a tree when you are not looking and you see her out of the corner of your eye and she disappears. Then you TRY to see her every day after without success until you are not trying and then she will appear again when you least expect it."
And this is the total secret to your advancement and understanding of your Tai Chi practice. Simply DO IT! No silly mind games, no thinking low, or I must sink my qi, no thinking of honey rolling down your body etc., or the many other games that we are told to play as these are all CONSCIOUS thought and another important classic saying that
I was told way back was that:
"Conscious thought will block the Qi flow".
However, one of the most difficult things is to NOT think while performing your Taiji form. And most people will TRY to block all thought from their mind. This is incorrect as TRYING to block conscious thought is in itself conscious thought and more so that normal thoughts that come and go in your mind while you practice. If you cannot rid your mind of all thought (and of course if you KNOW that you are doing this then you AREN'T), then it is much better to allow any thoughts to come and go while you practice, as long as they are thoughts completely different to what you are actually doing and that those thoughts do not cause tension to rise into the upper body. Normal thoughts like what you will be doing next after your practice,m playing guitar or any really nice thought that will come and go. Never should you think not so nice thoughts like revenge or hatred etc. Even if you simply think about the surrounding countryside (if you are practicing in the outdoors) or the birds chirping, that is good enough to cause the Qi flow to sink.
However, there is another way that Tai Chi allows the Qi flow to sink naturally and this is one of the main reasons that we perform the form with bent legs. We would of course never actually defend ourselves with this bent leg position and this is a big mistake that most make when teaching Tai Chi as a fighting art, they think that we must use Tai Chi exactly as it is in the postures. However, this is incorrect. We have bent knees in order for the conscious mind to FEEL the pressure in the thighs. This in turn tells the sub-conscious mind that we are SINKING. And another classic saying that we are always told in the beginning that: " What the physical does, so too does the Qi" . So when we SINK our body physically by bending the knees, the sub-conscious mind will cause the Qi also to SINK to the tantien leaving the rest of the body to simply move in accordance with each posture thereby causing the Qi to become activated in each particular meridian in turn which is wonderful for health.
This sub-conscious SINKING also allows us to issue forth Qi when we must defend ourselves. However, again, if we think about doing this, it will never happen. This is why Tai Chi and Bagua can never be used in a tournament sport situation or stupid push hands competitions, because we are constantly thinking about what will happen next and how we will defeat it. This is conscious thought and so the Qi will not be issued. Another reason is that God made us such that we could not hurt others needlessly using the great power of Qi and in a sport, there is no need for this so it will never happen! The only time the Qi will be issued forth is when we least expect it, when the shy girl is peeping at us from behind the tree. And this means when we are attacked in the street when we least expect it. This has happened to be on a number of occasions in my miss-led 20s and 30s where I have felt that immense power of Qi. But in each incident when I would try to gain that power again, it was gone because I was TRYING!
Another area where the Qi flow will manifest automatically is in the healing area when we come across someone who needs healing. If we were to consciously THINK about the Qi going into this person, it would not work at all. However, healing is also exactly the same as being attacked suddenly, it works when you least expect it. And here is where that lovely saying is so true: "You are only a true healer if your patient is healed as they walk from your door to your desk". In other words, the real healing happens not by the needles that you will stick, nor by the herbal remedy that you will prescribe or the pills, nor by the massage that you will impart; it will happen before you even talk to the patient. The physical things are important of course like laying on of hands etc, but the beginning activation of Qi happens simply because you have come in contact with someone who is ill. And it is every animal's automatic obligation to heal others who are ill. I have seen this happen in the wild or with family pets many times. Even to the point where an injured animal who cannot be fixed, will be chewed up by another animal because that was the only course of action.
It is really easy to get the Qi flow to sink and it is really difficult at the same time. However, as I keep saying over and over; all you have to do, is the movement. Every great secret about Tai Chi and Bagua is locked up in the movement, nothing else. It cannot be intellectualized, it is a purely physical thing which when done correctly (and herein lies the most important thing) will impart to the practitioner all of the wonderful benefits that all internal systems have to offer. Sadly though in modern times even in China, these wonderful arts have been watered down so much that they have become nothing! They have been denigrated by those who would put them into national and international tournaments to see who is best. So the internal part is lost, and as they are INTERNAL arts, what you are left with are arts that are empty shells which cannot be used for self defence or healing, so people resort back to things like Karate and other hard styles whereby the chap with the biggest muscles always wins.