The nature of prana is light. It is a form of energy existing everywhere, within us and outside us. It is a force capable of being dispersed as well as concentrated within the body. The method of controlling the flow of prana, its concentration and dispersal is pranayama. The mind can also influence the flow of prana to different parts of the body to combat disease; this is known as prana vidya.
According to yoga, within the physical body is a subtler body known as the pranayama kosha, which forms the subtle network through which prana flows. It is also known as the pranic, etheric or bioplasmic body. This energy body is said to have the same shape as the physical body, however, through concentration and visualisation it is able to expand and contract.
Researchers working with the Kirlian high voltage photographic apparatus obtain what is believed to be photographs of this subtle pranic field. It is within the realm of this field that bio-energy is generated, stored and then circulated in the body through the network of nadis.
The pranic field is sometimes called psi plasma due to the fact that it can be likened to the plasma (charged gases) studied in plasma physics. It is a vapour of charged particles which can be affected internally by the mind and externally by electric, magnetic, or electromagnetic fields.
"Just as an emperor posts his officials in different parts of his realm, similarly the chief prana allots functions to the lower pranas." Prashanopanishad
Traditionally prana is divided into five zones in the body. These subdivisions are as follows:
There is another subdivision of the pranic force called the upa pranas. They are responsible for minor transformations of energy, as for example, when we sneeze, yawn, belch, hiccup or blink our eyes. These minor or upa pranas are called naag, kurma, krikara, devadutta and dhananjaya. Traditionally these pranas are controlled by vayus, currents or winds, which are generated by the process of breathing and, allied with that, certain practices of concentration. The vayus are like energy corridors along which each particular division of the pranic force flows, internally and also externally.
"From prana indeed all living forms are born and, having been born, they remain alive by prana. At the end they merge into prana once more." Taittiriya Upanishad
Mahaprana (great prana) is the cosmic, universal, all encompassing energy out of which individuals draw sustenance through the breathing process. The various pranas in the body are at once a part of this mahaprana, and also separate from it. There is a story from the Prashnopanishad which explains this:
"...The deities (of the body) are ether, air, fire, water, earth, speech, mind, eye and ear. Seeing their own splendour they boasted, 'We are the rulers of the body because we are its supporters'. But prana, the chief amongst them, reproved them saying, 'Don't delude yourselves. It is I alone, dividing myself fivefold, who supports and keeps the body intact.' But the other deities were incredulous. Prana, in a fit of wrath, drew himself out of the body. Immediately ail the deities found themselves leaving it with him, and when prana returned, the deities found themselves back in their former places. Just as bees leave the hive when their queen departs and return when she returns, so did the deities behave. Satisfied with this evidence the deities then gave worship to prana."
The Upanishads state that there are two aspects of man's existence- prana and consciousness. Prana is the vital or bio-plasmic energy, which is universal in nature, and consciousness is knowledge. Prana is known as the active, and consciousness the dormant aspect of our existence. Consciousness, the spirit principle, is called purusha (literally 'that which sleeps in the city'). Prana, the nature principle, energy and matter, is called prakriti (literally 'activity').
Purusha must always work in co-operation and in union with prakriti. Without prana, consciousness is unable to create. There must be an underlying force which is transformed into various objects and forms. On the higher level of experience, prana and consciousness are one. On the mundane level of existence, however, they are mutually related, and interact one with the other. They are in fact mutually dependent entities, at times merging and at times becoming separate. Prana can thus be affected by consciousness and vice versa.
What are the ways of understanding the nature of our existence? Prana can be understood and realised by the systematic study of the dimensions of our consciousness. This, however, is the most difficult way because it implies that there must be a direct perception into the nature of consciousness which is not possible for most people.
An easier way of understanding and realising the dimensions of our consciousness is to study and realise the different aspects of prana in the body through the yogic techniques such as meditation and pranayama. Since prana is the force within the breath and the body, it is the most amenable to study. By the practices of swara yoga we can gain an insight into the more subtle levels of our consciousness and existence.
This way is open to everyone and it is certainly possible for us to follow this path. This is also the path followed by physicists, psychologists, para-psychologists, and is basically the idea behind the work being done on Kirlian photography and biofeedback, may be compared with getting to know someone by first looking at their reflection in the mirror from 11 sides, and waiting until the time is right before turning and looking directly at him.