Answer: The purpose of cultivating meditative concentration (samādhi) is to cultivate the mind, to make the mind cease. Although bodily stillness can reduce the mind's agitation and help the mind become still, if the mind is very pure in the samādhi of bodily stillness, then when the practice becomes mature, one can likewise maintain mental cessation and mental samādhi even during regular bodily movement. It is somewhat more difficult, but it is possible to have the body moving while the mind does not move. When the body moves but the mind does not, one encounters more conditions, which better tests the mind's power of concentration; at the same time, the causes and conditions for realizing the Path also increase greatly, which is rather advantageous for investigating Chan (canchan). Even the elimination of self-view (ātma-dṛṣṭi) can be accomplished while the body is in motion—contacting conditions and encountering circumstances can spark inspiration, thereby realizing emptiness.
At the same level of meditative concentration, the samādhi with the body moving demonstrates more fully the depth of one's cultivation of concentration than the samādhi with the body still, and the power of concentration is more solid. This needs to be nurtured and maintained by the samādhi of bodily stillness in quietude; cultivating both together will complement each other and mutually promote progress. Generally speaking, complete bodily stillness is also a kind of obstruction, unfavorable for strengthening the power of concentration. Therefore, after sitting for a period of time, one should rise and practice walking meditation (jingxing), moving about a little; the circulation of qi and blood becomes smoother, the mind becomes more tranquil, and the mind's thinking becomes deeper and more penetrating.
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