4. Breath Control and 'Kiai'

Breath-control has been described as being 'zen itself in its physiological aspect'. Even before schools of Zen existed the relation of breath-control to awareness was a major preoccupation of Indian 'yoga' and chinese 'taoism'.

One's rhythm of breathing is, after all, affected by either the physical or mental state that one is in. When exhausted after training, one breathes heavily; when excited, one breathes quickly; when one laughs, the emphasis is on the outbreath; when one cries, or is afraid, the emphasis is on the inbreath. But also it can work the other way: one can affect the mental and physical condition by controlling one's rhythm of breathing.