The quieting of the mind-stuff, and the elimination of the waves of desire, attraction and repulsion and egoistic reactions prepares the seeker for the liberating practices that open up the being to higher energies and capacities. Without that preparation, the ultimate aims of Raja Yoga cannot be achieved, but they remain preliminary. The next stage integrates Asana, Pranayama and Mantra. Asana in Raja Yoga is simplified down to its basic elements: a comfortable and secure posture that allows the head and neck to be aligned in a straight line, and which can be held unmoving for a sustained period of time without discomfort or pain. Whereas in Hatha Yoga, the use of Asana is a central practice with numerous different poses coming into play, Raja Yoga moves quickly to the essential point of allowing the psycho-physical energies to come into play, be held and circulated, and to do so in a stable mental, emotional, nervous and physical body. It is really the action of Pranayama combined with Mantra that represents the core method of Raja Yoga that can lead to the results of the forms of meditation, concentration and Samadhi that represent the next and final stages of the practice.
Sri Aurobindo observes: “In order to bring about this manifestation the present nodus of the vital and physical body with the mental being has to be loosened and the way made clear for the ascent through the greater psychic being to the union with the superconscient Purusha. This can be done by Pranayama.”
“The Rajayogic Pranayama purifies and clears the nervous system; it enables us to circulate the vital energy equally through the body and direct it also where we will according to need, and thus maintain a perfect health and soundness of the body and the vital being; it gives us control of all the five habitual operations of the vital energy in the system and at the same time breaks down the habitual divisions by which only the ordinary mechanical processes of the vitality are possible to the normal life. It opens entirely the six centres of the psycho-physical system and brings into the waking consciousness the power of the awakened Shakti and the light of the unveiled Purusha on each of the ascending planes. Coupled with the use of the Mantra it brings the divine energy into the body and prepares for and facilitates that concentration in Samadhi which is the crown of the Rajayogic method.”
Sri Aurobindo, The Synthesis of Yoga, Part Two: The Yoga of Integral Knowledge, Chapter 28, Rajayoga, pp. 517-518