Starting from the physical body, the Hatha Yogin first attempts to create a solid and unruffled physical instrument that can hold any amount of energy that is required. This basis is achieved through asana, the physical postures for which yoga has become well-known in modern times. Sri Aurobindo continues: “By its numerous Asanas or fixed postures it first cures the body of that restlessness which is a sign of its inability to contain without working them off in action and movement the vital forces poured into it from the universal Life-Ocean, gives to it an extraordinary health, force and suppleness and seeks to liberate it from the habits by which it is subjected to ordinary physical Nature and kept with the narrow bounds of her normal operations.”
Legend has it that such control over the physical body can be achieved as to develop powers such as levitation. This is said to occur when Asana is tied to the practices of Pranayama, which is the control of the vital force through management of the breath. “…for breathing is the chief physical functioning of the vital forces. Pranayama, for the Hathayogin, serves a double purpose. First, it completes the perfection of the body. The vitality is liberated from many of the ordinary necessities of physical Nature; robust health, prolonged youth, often an extraordinary longevity are attained. On the other hand, Pranayama awakens the coiled up serpent of the Pranic dynamism in the vital sheath and opens to the Yogin fields of consciousness, ranges of experience, abnormal faculties denied to the ordinary human life while it puissantly intensifies such normal powers and faculties as he already possesses. These advantages can be farther secured and emphasised by other subsidiary processes open to the Hathayogin.”
One of the major subsidiary processes referred to are called Bandhas or “locks” whereby certain areas of the body are systematically controlled and energy sealed off by the Hathayogin to redirect the flow and intensity of the pranic energy. When combined with Asana and Pranayama, the Bandhas act to forcefully focus and increase the Prana, yielding yet further progress for the Hatha Yogin’s quest.
Sri Aurobindo, The Synthesis of Yoga, Introduction: The Conditions of the Synthesis, Chapter 4, The Systems of Yoga, pg. 29