It's rare in taiji quan to find movements or postures in which both right and left arms are given equal importance. No matter what taiji style or form, most often one arm leads and the other follows.
This same principle is mirrored in our social structures--family, government, corporations, schools, and so on. Some people are leaders, decision-makers, risk-takers, trend-setters. Others live quieter lives or assume roles that maintain, support, and help get the job done. Though all roles, from top to bottom, are vital in a well-functioning society, quite naturally we give most value to our leaders. Olympic gold medal or royal scandal, they make the headlines and grab our attention.
In taiji quan, it's easy to spot the leader. The major arm or hand is usually more forward and placed in a central position. It's important, prominent, and the eye is drawn to it. While we practice, we always try to move it correctly and make sure it ends up in the right spot. Of course this is good, but it's just not enough.
Though most practitioners move the second hand according to the general requirements of the form, they usually treat it like a movie extra--it's in the background, unfocused, uninteresting, and ignored. In fact, this second, "minor" hand also needs quality attention and training. It must be trained to move with the same level of precision as the first. Without this, our taiji quan practice is incomplete.
This is a widespread problem among taiji quan lovers, including my own students and kung fu brothers. It's one of the main reasons why even the hardest working students get stuck. Their taiji quan can not advance because they haven't paid enough attention to this second hand. Often they will practice hard to perform a move correctly but let the second hand do "whatever". They work to make sure the final postures are accurate but don't pay attention to the improper position of their minor hand.
It's become clear from my own experience practicing and teaching kung fu, that there is no such thing as a major hand and minor hand. Both are equal in importance. Take a close look at an expensive, finely tailored jacket. The inner lining is made of quality materials and constructed equally as well as the outer surface. With cheap clothing, the external surface may look great but it's a different story inside.
Kung fu usage demands whole-body coordination, every part cooperating fully to reach the target and defeat the opponent. So any carelessness with the supporting hand--sloppy movement or inaccurate placement-- will undermine the primary hand's mission. At the very least, delivery of the usage will be less effective. It's even possible that the major hand won't be able to do its work.
How we handle the inner hand also makes a difference if our primary reason for practicing taiji quan is to maintain health. Unless some type of handicap or special problems are present, motions that extend outward pose very little difficulty for all of us. We open up our arms, swing them around, reach out to grab something, step out, kick out, and stretch our limbs all the time, without any thought. What about our torsos? They don't even begin to get equal time for exercise.
In our taiji quan practice, the inner hand can help with this. Because it's normally held closer to body, it's easier to use it as a link that draws attention to our body. This is important because our internal organs are situated in the chest and abdomen, not the arms and legs. By its very proximity, then, this arm can remind us to expand our torsos as our arm moves outward and compress as it presses inward. When our arms trace the circular movements of the chan si jing (silk reeling energy), our second hand remind us that the graceful spirals originate with the torso. And when the torso joins in, our inner organs receive a revitalizing massage. Therefore, from a strictly health-oriented viewpoint, the second hand actually becomes our major hand.
Our second hand is also a big player in our mental training. Taiji quan is based on the taiji philosophy from China. If our practice is to reflect this ancient philosophy, then we must learn to function within a mental paradox: our awareness must be intensely focused; simultaneously, our awareness must also spread out, extend, and be divided to take care of different areas of our bodies all at once while we perform taiji quan's movements and postures. As we struggle for correct coordination, accurate placement, and precise movement of our second hand, we are also strengthening our will, enlarging our mental abilities, and opening new doors of action and perception.