Prana is in the atmospheric air, but it is also elsewhere, and it penetrates where the air cannot reach. The oxygen in the air plays an important part in sustaining animal life, and the carbon plays a similar part with plant life, but Prana has its own distinct part to play in the manifestation of life, aside from the physiological functions.

We are constantly inhaling the air charged with prana, and are as constantly extracting the latter from the air and appropriating it to our uses. Prana is found in its freest state in the atmospheric air, which when fresh is fairly charged with it, and we draw it to us more easily from the air than from any other source. In ordinary breathing we absorb and extract a normal supply of prana, but by controlled and regulated breathing (generally known as Yogi breathing) we are enabled to extract a greater supply, which is stored away in the brain and nerve centers, to be used when necessary. We may store away prana, just as the storage battery stores away electricity. The many powers attributed to advanced occultists is due largely to their knowledge of this fact and their intelligent use of this stored-up energy. The Yogis know that by certain forms of breathing they establish certain relations with the supply of prana and may draw on the same for what they require. Not only do they strengthen all parts of their body in this way, but the brain itself may receive increased energy from the same source, and latent faculties be developed and psychic powers attained. One who has mastered the science of storing away prana, either consciously or unconsciously, often radiates vitality and strength which is felt by those coming in contact with him, and such a person may impart this strength to others, and give them increased vitality and health. What is called "magnetic healing" is performed in this way, although many practitioners are not aware of the source of their power.

Western scientists have been dimly aware of this great principle with which the air is charged, but finding that they could find no chemical trace of it, or make it register an any of their instruments, they have generally treated the Oriental theory with disdain. They could not explain this principle, and so denied it. They seem, however, to recognize that the air in certain places possesses a greater amount of "something" and sick people are directed by their physicians to seek such places in hopes of regaining, lost health.

The oxygen in the air is appropriated by the blood and is made use of by the circulatory system. The prana in the air is appropriated by the nervous system, and is used in its work. And as the oxygenated blood is carried to all parts of the system, building up and replenishing, so is the prana carried to all parts of the nervous system, adding strength and vitality. If we think of prana as being the active principle of what we call "vitality," we will be able to form a much clearer idea of what an important part it plays in our lives. Just as is the oxygen in the blood used up by the wants of the system, so the supply of prana taken up by the nervous system is exhausted by our thinking, willing, acting, etc., and in consequence constant replenishing is necessary. Every thought, every act, every effort of the will, every motion of a muscle, uses up a certain amount of what we call nerve force, which is really a form of prana. To move a muscle the brain sends out an impulse over the nerves, and the muscle contracts, and so much prana is expended. When it is remembered that the greater portion of prana acquired by man comes to him from the air inhaled, the importance of proper breathing is readily understood.

It will be noticed that the Western scientific theories regarding the breath confine themselves to the effects of the absorption of oxygen, and its use through the circulatory system, while the Yogi theory also takes into consideration the absorption of Prana, and its manifestation through the channels of the Nervous System. Before proceeding further, it may be as well to take a hasty glance at the Nervous System.

The Nervous System of man is divided into two great systems, viz., the Cerebro-Spinal System and the Sympathetic System. The Cerebro-Spinal System consists of all that part of the Nervous System contained within the cranial cavity and the spinal canal, viz., the brain and the spinal cord, together with the nerves which branch off from the same. This system presides over the functions of animal life known as volition, sensation, etc. The Sympathetic System includes all that part of the Nervous System located principally in the thoracic, abdominal and pelvic cavities, and which is distributed to the internal organs. It has control over the involuntary processes, such as growth, nutrition, etc.

The Cerebro-Spinal System attends to all the seeing, hearing, tasting, smelling, feeling, etc. It sets things in motion; it is used by the Ego to think-to manifest consciousness. It is the instrument with which the Ego communicates with the outside world. This system may be likened to a telephone system, with the brain as the central office, and the spinal column and nerves as cable and wires respectively.

The brain is a great mass of nerve tissue, and consists of three parts, viz., the Cerebrum or brain proper, which occupies the upper, front, middle and back portion of the skull; the Cerebellum, or "little brain," which fills the lower and back portion of the skull; and the Medulla Oblongata, which Is the broadened commencement of the spinal cord, lying before and in front of the Cerebellum.

The Cerebrum is the organ of that part of the mind which manifests itself in intellectual action. The Cerebellum regulates the movements of the voluntary muscles. The Medulla Oblongata is the upper enlarged end of the spinal cord, and from it and the Cerebrum branch forth the Cranial Nerves which reach to various parts of the head, to the organs of special sense, and to some of the thoracic and abdominal organs, and to the organs of respiration.

The Spinal Cord, or spinal marrow, fills the spinal canal in the vertebral column, or "backbone." It is a long mass of nerve tissue, branching off at the several vertebrae to nerves communicating with all parts of the body. The Spinal Cord is like a large telephone cable, and the emerging nerves are like the private wires connecting therewith.

The Sympathetic Nervous System consists of a double chain of Ganglia on the side of the Spinal column, and scattered ganglia in the head, neck, chest and abdomen. (A ganglion is a mass of nervous matter including nerve cells.) These ganglia are connected with each other by filaments, and are also connected with the Cerebro-Spinal System by motor and sensory nerves. From these ganglia numerous fibers branch out to the organs of the body, blood vessels, etc. At various points, the nerves meet together and form what are known as plexuses. The Sympathetic System practically controls the involuntary processes, such as circulation, respiration and digestion.

The power or force transmitted from the brain to all parts of the body by means of the nerves, is known to Western science as "nerve force," although the Yogi knows it to be a manifestation of Prana. In character and rapidity it resembles the electric current. It will be seen that without this "nerve force" the heart cannot beat; the blood cannot circulate; the lungs cannot breathe; the various organs cannot function; in fact the machinery of the body comes to a stop without it. Nay more, even the brain cannot think without Prana be present. When these facts are considered, the importance of the absorption of Prana must be evident to all, and the Science of Breath assumes an importance even greater than that accorded it by Western science.