e is proportionate to the quantity of carbonic acid he
exhales in a certain period of time. The Yogis never use salt, and live
entirely on milk, which they take only during the night. They move very
slowly in order not to breathe too often. 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. "It is the fourth stage or division of
Yoga."

The Pranayama consists of three parts. The first excites the secretion
of sweat, the second is attended by convulsive movements of the
features, the third gives to the Yogi a feeling of extraordinary
lightness in his body.

After this, the Yogi practises Pratyahara, a kind of voluntary trance,
which is recognizable by the full suspension of all the senses. After
this stage the Yogis study the process of Dharana; this not only stops
the activity of physical senses, but also causes the mental capacities
to be plunged into a deep torpor. This stage brings abundant suffering;
it requires a good deal of firmness and resolution on the part of a
Yogi, but it leads h