I'm talking about sitting as a physical posture. People sit a lot every day in the office, at home, in a restaurant, in the car, etc. ....
What makes sitting more intensive and direct? How does intensity and directness depend on sitting?
Sitting is the preeminent yogic posture for meditation. The best posture is with legs crossed in lotus , then in half lotus, then in Burmese, then in Western. The back is then held straight, etc. (this detail differs from tradition to tradition slightly - in Taoism for example a straight back means a slightly rounded back). This posture straightens or opens the channels and facilitates deep concentration. As a yogic posture it just does this.
One can also sit in a chair if the back or hips are injured and even meditate laying on one's back. But they do not facilitate concentration in the same way and definitely not to the same degree.
Walking meditation is in part to help people bring their expression of Buddha out into the world (TNH says this in one of his works too).
and once a Chan monk told me that doing prostrations is the best.
For purification/Buddha repentance practice.
Many simply say that posture is not that important.
It is important, it's just not absolutely critical as meditation is done with the mind. But there is no other posture that facilitates long term deep concentration.
_________________Kirt's Tibetan Translation Notes
"Only you can make your mind beautiful."
HH Chetsang Rinpoche