Prana may be defined as the finest vital force in everything which becomes visible on the physical plane as motion and action and on the mental plane as thought. The word pranayama, therefore, means the restraint of vital energies. It is the control of vital energy which tingles through the nerves of persons. It moves his muscles and causes him to sense the external world and think his internal thought.
Tasmin sati svasaprasvasayor gativicchedah pranayamah.
Regulation of breath or the control of prana is the stoppage of inhalation and exhalation, which follows after securing that steadiness of posture or seat.
This is the definition of pranayama in the Yoga Sutras of Patanjali (2:49). Svasa means inspiratory breath. Prasvasa means expiratory breath. You can take up the practice of pranayama after you have gained steadiness in your asana. If you can sit for three hours in one asana, continuously at one stretch, you have gained mastery over the asana. If you are able to sit from half to one hour even, you can take up the practice of pranayama. You can hardly make any spiritual progress without the practice of pranayama.
Prana is vyashti, single or individual prana, when the individual is concerned. The sum total of the cosmic energy or cosmic prana is Hiranyagarbha who is known as the floating ‘Golden Egg’. Hiranyagarbha is samashti prana, cosmic prana. One match stick is vyashti, single. The whole match box is samashti. A single mango tree is vyashti. The whole mango grove is samashti.
The energy in the body is prana. By controlling the motion of the lungs or respiratory organs, we can control the prana that is vibrating inside. By control of prana, the mind can be easily controlled, because the mind is fastened to the prana, like the bird to the string. Just as the bird that is tied to a post by a string, after flying here and there, finds its resting place on the post, so also this mind-bird after running hither and thither, in various sensual objects, finds its resting place during deep sleep in the prana.
Apane juhvati pranam pranepanam tathapare; Pranapanagatee ruddhva pranayamaparayanah.
Others offer prana (outgoing breath) in apana (incoming breath) and apana in prana, restraining the passage of prana and apana, absorbed in pranayama. (4:29)
Pranayama is a precious yajna, sacrifice. Some practise the kind of pranayama called puraka, filling in. Some practise the kind of pranayama called rechaka, emptying. Some are engaged in the practice of pranayama called kumbhaka, by impeding the outward passage of air, through the nostrils and the mouth, and by impeding the inward passage of the air, in the opposite direction.
Prana is the sum total of all energy that is manifest in the universe. It is the sum total of all the forces in nature. It is the sum total of all latent forces and powers which are hidden in men and which lie everywhere around us.
Heat, light, electricity, magnetism are the manifestations of prana. All forces, all powers and prana spring from the fountain or common source, atman.
All physical forces, all mental forces come under the category ‘prana’. It is a force on every plane of being, from the highest to the lowest. Whatever moves or works or has life, is but an expression or manifestation of prana.