Movement increases the exhaled carbonic acid, and so
the Yoga practice prescribes avoidance of movement. The quantity
of exhaled carbonic acid is also increased by loud and lively talking:
so the Yogis are taught to talk slowly and in subdued tones, and
are even advised to take the vows of silence. Physical labor is
propitious to the increase of carbonic acid, and mental to its
decrease; accordingly the Yogi spends his life in contemplation
and deep meditation. Padmasana and Siddhasana are the two methods
by which a person is taught to breathe as little as possible.
Suka-Devi, a well-known miracle-monger of the second century B.C. says:
"Place the left foot upon the right thigh, and the right foot upon
the left thigh; straighten the neck and back; make the palms of
the hands rest upon the knees; shut the mouth; and expire forcibly
through both nostrils. Next, inspire and expire quickly until you
are fatigued. Then inspire through the right nostril, fill the
abdomen with the inspired air, suspend the breath, and fix the
sight on the tip of the nose. Then expire through the left nostril,
and next, inspiring through the left nostril, suspend the breath... "
and so on.
"When a Yogi, by practice, is enabled to maintain himself in one
of the above-mentioned postures for the period of three hours, and
to live upon a quantity of food proportional to the reduced condition
of circulation and respiration, without inconvenience, he proceeds
to the practice of Pranayama," writes Dr. Paul.
