To illustrate the concept of incremental variations, let's also introduce a new exercise.
Beginning with your feet positioned about 1.5 shoulder-widths apart, toes pointed just to the outside of straight ahead (about 15°) and knees slightly bent, upper arms hanging loosely at your sides, elbows bent so that your forearms extend in front of you, parallel to the ground, palms facing towards each other, and hands level but otherwise limp, rotate your left forearm so that your left palm points down, even slightly outward if you can do so without pain, and move your right hand across in front of you until it is above your left hand.
Rotate your body slightly to the left, also shifting your weight slightly to the left, and allow your right heel to move slightly outward (to the right) while you slowly push another inch or two to the left with both hands, right above left.
Now, in one motion, pull your right hand towards your body and then down, brushing the inside of your left elbow with you right fingertips, begin to rotate your left hand back towards the palm-inward position, pull your right heel back to its original position, and turn your body back towards facing straight ahead, re-centering your weight.
Now to the right, sweeping your right hand slowly to the right, rotating it down and outward, and move your left hand to the right a little faster, so that it catches up with the right hand, left over right, turning your body slightly to the right and shifting your weight to the right, while allowing your left heel to move slightly outward (to the left). Push both hands an inch or two past your right elbow.
Pull your left hand towards your body and down, brushing the inside of your right elbow and then rotating down and outwards as it moves in front of your body to the left, with the right hand rotating back to the palm-inward position as it also moves in front of your body, rising above the left hand as it catches up with it. Meanwhile, pull your left heel back in, rotate your body and shift your weight to the left, and allow your right heel to move slightly outward.
Repeat until your hands are flowing continuously, instead of reciprocating, and your feet are making the little adjustments they must make automatically.
Now begin to spread your hands further apart vertically as they reach the outer limits of their movements, so they at first make larger circles, then sweeping arcs, then even larger sweeping arcs. Try to do this stepwise, so that each iteration is slightly more expansive than the last but it takes at least twenty repetitions to move from the petite version of the exercise to the most extensive.
(As you become more accustomed to this, and as you gain strength and flexibility, you'll find yourself reaching further to the outside, bending your knees more deeply, and shifting more of your weight.)
There is a point in the escalation of this exercise beyond which it is impossible to maintain recirculating motion, necessarily reverting to reciprocation, because one hand is reaching so high and the other so low (and/or so far behind your back) that they are both exploring corners (cusps), through which no smooth paths exist in your freedom of movement. Go ahead and explore these cusps, when you reach sufficient flexibility to do so, but don't forget to take your time getting to them by very gradually escalating the extension of the movement up to the limit of recirculation, and also be careful not to throw yourself into those cusps more vigorously than your muscles and tendons can handle. By their very nature, cusps limit your options, so be alert to the possibility that you might lose your balance while in an extreme position from which there is only one direction of retreat and go at it carefully.
Henceforth I will use "reciprocating" to mean movement into and out from a cusp, and "recirculating" to mean a flowing sequence of movements that is free of cusps.
This exercise, rather than the first, is the foundation of my practice, and it has more variations than the one already described. I'll get into those in a future installment.