"
Within every moment of thought you should see yourself that your
fundamental nature is pure. You should cultivate for yourself, pratice for
yourself, and accomplish for yourself the enlightenment of buddhahood."
--Huineng
[1]
What the legs are doing is the least important and causes the most pain and fear for many people. Seated meditation can be done in a chair or on the floor - either cross legged or kneeling. There is no mystical value of one position over another, although some positions provide greater stability and long-term ease. What really matters is that the thighs slope down from the pelvis to the knees enough to tilt the pelvis forward. This provides support for the low back.
The classic position is full lotus, which requires significant hip and leg flexibility. In full lotus, the legs are crossed, and each ankle is lifted up and placed over the top of the opposite thigh. In half lotus, only one leg is up. Either lotus posture is recommended only when they are easy to maintain; the purpose of the posture is to be comfortable and balanced, so forcing oneself into an awkward position is not helpful.
The most common sitting position for westerners is ‘Burmese,’ in which the legs are crossed, with both feet down. In Burmese, the front surface of the shins rests on the ground. One calf is in front, and the other tucks between the calf and leg of the opposite leg, so that neither leg crosses on top of the other. Ideally the knees are firmly on the ground, if they do not stretch that far, support them with a cushion or folded blanket. For all cross-legged postures, it is advisable to switch legs regularly, so that the leg that is on top or in front alternates. This keeps one reasonably symmetrical; loosening up the hips, pelvis and leg on just one side can gradually pull the spine out of alignment.
Another option is seiza, or kneeling postures. These can be done sitting on a bench, or with a cushion or two between your legs. Kneeling is often more comfortable for people with less flexibility in the hips, and is the easiest position to get in or out of. Make sure you can tilt the pelvis forward, establishing the curve in the lower back just like in cross-legged postures. When sitting in a chair or tall bench, you may have to add a cushion to tilt the seat in order to help the thighs slant down and establish a good position for your low back.
Posture
> --Legs
---Torso
---Hands and head
Breath
Bowing
Mind
Where
When