Nature. The primal matter with three different innate qualities (Guṇas:Qualities of Mind - Sattva:Good, Rajas:Passionate, Tamas:Dull) whose equilibrium is the basis of all observed empirical reality.
Pranayama in Hindu Yoga is the regulation of breath through certain techniques and exercises. It is a conscious prolongation of inhalation, retention and exhalation. 'Prana' pronounced 'Praanaa' is the Life Energy, both individual and universal. If breath is controlled, mind is controlled and becomes quiet and vice versa. It is used as an aid to meditation, relaxation, calming the mind and general health.