A wall is something that stops you, anything that stops you.
If you overdo exercise, exhaustion and soreness can become a wall.
If you do your exercises mechanically, the same way every time, boredom can become a wall.
In the context of the martial arts, if you concern yourself overmuch with application – how effectively a sequence of movements might be applied in combat – or with precise form and maximal dynamism, you may find that you've walled yourself off from all of the various possibilities that can be present at each step, in a more playful approach. And, too, there's legitimate reason for concern that practicing in a violent manner can make one more likely to participate in or even initiate violence, and less apt to take the opportunity to avoid a needless fight.
Similarly, I'm finding that the effort to accurately describe something that is never exactly the same, should never be exactly the same from one moment to the next, can become a wall, both to the work of description and to the practice.
On the other hand, there are still a few ideas that I have yet to touch on, the theory that I mentioned in the original post on this blog.
You already have the basics, stances (with particular attention to positioning of the knee) and recirculating arm motions supported by subtle alterations of those stances (reciprocating motions when exploring cusps), and a small collection of principles to act as a guidebook. While I prefer not to constrain your imagination with respect to what motions you might wish to include in your repertoire, I hope and intend to fill out that guidebook.
Reach to the back of your head and find the little bump at the top of your neck. On the inside of your skull, most of the tissue within a couple inches of that point is contained in the cerebellum. The cerebellum is fundamentally an integration machine. (Integration, along with differentiation, form the basis of calculus. Integration is essentially the accumulation of an effect as the factors creating that effect also change.) The cerebellum measures the effect of various and varying forces upon momentum, your momentum or that of something you handle, throw, or sense remotely. It also makes predictions about the effects of forces that haven't yet occurred. And it does all this incredibly fast, but it needs experience upon which to base what it does.
Along with stretching, strengthening, and mild cardiovascular exercise, the main point of practice is to provide the cerebellum with some experience upon which to base its predictions. The more varied that experience, the better able it will be to handle something totally novel, something it has never had to deal with before. Also, the more diverse the range of situations with which it has learned to cope, the more gracefully it will be able to guide your motion under ordinary circumstances.
The upshot of this is that it is better to ferret out the essence of what your body wants to do today than to stress over whether you are performing some movement correctly. Protect your knees, find something soft to land on if you're doing something that may cause you to lose your balance, and otherwise allow your cerebellum sufficient license to explore variations on motions, even beyond the point of their becoming unrecognizable. Thus liberated, it will guide you well.