Taiji is an intelligent system, refined over thousands of years, that offers a proven method for working on the "self-sensing" taught by the Sufis. True taiji training involves much more than posture, choreography, or body mechanics. Some key concepts for our practice:

Sequence of events: 

deep mind intention [yi] > energizing and activation [qi] > forces [li] > movements 

We would consider focus on just the external movements and positions of the body as “level 0” i.e. not really training taiji at all.

For internal training we start with internal movements, and the 3 levels are working backward in time from the most easily observed last thing to happen, to refining our understanding of the subtler deeper, earlier processes:

level 1: Internal movements (most easily observed, like big obvious crest of wave)

level 2: Forces (more subtle before the internal movements, like beginning of wave rising)

level 3: Energizing and activation (much subtler and earlier, like subtle dip in water mile in ocean before obvious wave)

A deeper state of mind is needed in order to train earlier, more subtle, “higher” levels. 

To train the internal movements (1st level for beginners):

• focus on moving waist first to move upper body
• focus on shoulder to move arm/hand

Beginners almost always try to move the hand before the shoulder and the upper body before the waist. Changing this takes sustained effort.

Unlike the 3 levels, the 3 timings are not an objectively “real” phenomena, but are a training method to train the 3 levels (i.e. have to look in the right place in the right time to find the right part of the wave because that’s where it appears). The involve moving the mind ahead in space at a given moment of the movement depending on the level being trained (internal movements, forces that precede the movement, or energizing and activation that precede the forces)

Patrick Kelly articulated the details of this method very clearly in his teaching. He learned from Huang Xing Xian, who along with Ma Yueliang, Zheng Manqing, etc all understood this method and traditionally taught it only to close students.

Zheng Manqing said: there are no secrets 

Huang Xingxian added: just things too small to be seen

Patrick Kelly has appended: if there is a secret, it’s knowing where to put the mind and when

Awareness, intention, and intelligence; correspond to sensory, motor, interneurons 

Just training a quiet listening awareness will not develop your deep mind much. Intention must also be trained. Need a strong intention along with awareness of the result, and then intelligently refine the intention and try again, to develop the deeper mind intelligence. 

We train these 3 aspects across all levels. 

• On the physical etheric level, we do it by training the muscle phases (see below) in the taiji (strong effort to change how we organize them using these 3 aspects). 
• For deep emotional (astral)/deep mental (celestial) levels, we look for these 3 aspects in our meditation. (strong intention to cause an effect, awareness of result etc)

5 external: sight, sound, smell, touch, taste

• We use these in everyday external life 
• put them in the background in the taiji and focus on using internal sensors instead.

5 internal: pain, joint, muscle state (5 phases), pressure, heat

• pain means doing something stupid/very wrong and injuring body, try to avoid
• joint, muscle state, pressure sensors used to manage internal movements. Of these, only the muscle state can be directly affected by the motor neurons, so changing the muscle state is more or less only way to train the intention on the physical etheric level 
• heat sensors used for meditation, but not for managing movement in taiji

1) contraction (metal), muscle shortens and increases tension

2) release (water), muscle lengthens and decreases tension

3) stretch (wood), muscle lengthens while increasing tension

4) unstretch (fire), muscle shortens and decreases tension

5) neutral (earth)

Everyone knows how to contract since they are a baby.

Maybe half people can consciously release. 

Almost no one can consciously create an active stretch unless specifically train to do so.

• this is a source of the taiji elastic power. 
• Most people stretch passively by moving a joint near the limit of its range of motion, so the muscle unconsciously activates to resist as part of the body’s unconscious self defense response, while the person uses simple conscious intention to force the muscle to lengthen. 

Zheng Manqing made the cryptic comment that one must understand the 5 elements to use taiji as a martial art. He was referring to the 5 phases of the muscle cycle which he taught Huang Xingxian who in turn taught PK.