"Place the feet on the thighs, soles upward, palms in the middle of the groin, facing upward. Gaze at the nosetip, keeping the tongue pressed against the root of the upper teeth and the chin against the chest, and slowly raise the prana upward. This is called Padmasana, destroyer of all diseases. Ordinary people cannot achieve this posture, only the few wise ones on this earth can."
Hatha Yoga Pradipika, 1:45-47
The Lotus posture is the most iconic of all the yoga asanas and almost certainly the oldest. The unfolding of a comfortably held Lotus is considered to be the reward of a sincere and dedicated practice.
Padmasana is the traditional seat for the practices of pranayama and meditation. From this we can deduce that asana, as it is placed along the path of the eight limbs, is a preparatory practice. Preparation for what? For Padmasana and its potential. What potential? The potential for the "force in the pranic system and the higher faculties of the mind" to be awakened (Hatha Yoga Pradipika, commentary by Swami Muktibodhananda).
Energetically, Padmasana balances the forces of prana and apana in the body. Physically, it promotes blood flow to the vital organs of the abdomen and nourishes the sacral and coccygeal nerves (the subtle seat of kundalini) by decreasing blood flow to the legs.
When practicing Padmasana, do not force your legs into position. This is important. Let me repeat:
DO NOT FORCE YOUR LEGS INTO LOTUS POSITION.
I don't wish to enforce any seething rumors that yoga may in fact wreck your body, so work with me here and err on the side of caution. If you feel it in your knees, stop, exit, and regroup.
Gregor Maehle offers a nice step-by-step method for safely taking Padmasana in Ashtanga Yoga: Practice & Philosophy. His four-phase approach, which I have paraphrased below, has been enormously helpful to me in my own practice.
- Hug your right knee to your chest and close the knee joint completely by folding the right heel toward the right buttock. If the knee does not close, do not proceed.
- Hold the joint closed as you laterally (externally) rotate the thigh and draw your heel toward your groin. Think Janu Sirsasana A. If you feel pressure in the knee, do not proceed.
- Point your foot and cradle your leg so the foot and knee are level and draw the heel toward your navel. If your heel does not reach your navel without pressure in the knee, do not proceed.
- Fold the leg into place by now taking the right leg across your lap and lay the top of the right foot into the crease of the left hip. The soles of the feet should point up toward the sky, not toward the body.