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 fibres 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 being 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.

The Yogi teachings go further than does Western science, in one important feature of the Nervous System. We allude to what Western science terms the "Solar Plexus," and which it considers as merely one of a series of certain matted nets of sympathetic nerves with their ganglia found in various parts of the body. Yogi science teaches that this Solar Plexus is really a most important part of the Nervous System, and that it is a form of brain, playing one of the principal parts in the human economy. Western science seems to be moving gradually towards a recognition of this fact which has been known to the Yogis of the East for centuries, and some recent Western writers have termed the Solar Plexus the "Abdominal Brain." The Solar Plexus is situated in the Epigastric region, just back of the "pit of the stomach" on either side of the spinal column. It is composed of white and grey brain matter, similar to that composing the other brains of man.

It has control of the main internal organs of man, and plays a much more important part than is generally recognized. We will not go into the Yogi theory regarding the Solar Plexus, further than to say that they know it as the great central storehouse of Prana. Men have been known to be instantly killed by a severe blow over the Solar Plexus, and prize fighters recognize its vulnerability and frequently temporarily paralyze their opponents by a blow over this region.

The name "Solar" is well bestowed on this "brain," as it radiates strength and energy to all parts of the body, even the upper brains depending largely upon it as a store house of Prana. Sooner or later Western science will fully recognize the real function of the Solar Plexus, and will accord to it a far more important place than it now occupies in their textbooks and teachings.