Read Dharma Mittra's response:
Compiled by the sage Patanjali around 2,000 years ago, the eight limbs of yoga give you time-tested tools for achieving the ultimate goal of yoga—union with the Divine. Along the way, they can help you achieve radiant health, increased mental powers, and purity of mind and body.
Union with the Divine can never be achieved without practice of the first two limbs, the yamas and the niyamas. The five yamas (literally, "restraints") are ethical rules rather like the Ten Commandments; the five niyamas (literally, "things not to be restrained") are qualities to observe and cultivate. The five yamas are ahimsa (nonharming); satya (truthfulness); asteya (nonstealing); brahmacharya (sexual moderation); and aparigraha (nongrasping). The five niyamas are saucha (purity), samtosha (contentment), tapas (dedication), svadhyaya (self-study), and Ishvara pranidhana (devotion to the highest Self).
The third limb is asana, the postures that promote physical health and stamina. The fourth limb is pPranayama, the means for controlling breath and vital energy. The final goal of yoga can be achieved without these two limbs, but they can be invaluable in speeding you along the way.
The last four limbs are increasingly subtle methods of working with the mind. Pratyahara is the withdrawal of your senses from the material world in order to still the mind. Dharana is concentration, in which you strive to achieve one-pointed mental focus. Dhyana is meditation, which helps extend your uninterrupted concentration for longer and longer. And, samadhi, or superconsciousness, is union with the Divine—the doorway to bliss and the culmination of the yogic path.
Founder and director of the Dharma Yoga Center in N.Y.C., Dharma Mittra has spent 45 years disseminating the wisdom of yoga. Known as a teacher's teacher, he is also renowned worldwide as the creator of the Master Yoga Chart of 908 Postures, which inspired Yoga Journal's coffee-table book of asana photographs, Yoga (Hugh Lauter Levin Associates Inc., 2002).