This work will take up the Yogi "Science of Breath", which includes not only all that is known to the Western physiologist and hygienist, but the occult side of the subject as well. It not only points out the way to physical health along the lines of what Western scientists have termed "deep breathing", etc., but also goes into the less known phases of the subject, and shows how the Hindu Yogi controls his body, increasing his mental capacity, and develops the spiritual side of his nature by the "Science of Breath". The Yogi practices exercises by which he attains control of his body, and is enabled to send to any organ or part an increased flow of vital force or "prana", thereby strengthening and invigorating the part or organ. He knows all that his Western scientific brother knows about the physiological effect of correct breathing, but he also knows that the air contains more than oxygen and hydrogen and nitrogen, and that something more is accomplished than the mere oxygenating of the blood. He knows something about "prana,"of which his Western brother is ignorant, and he is fully aware of the nature and manner of handling that great principle of energy, and is fully informed as to its effect upon the human body and mind. He knows that by rhythmical breathing one may bring himself into harmonious vibration with nature, and aid in the unfoldment of his latent powers. He knows that by controlled breathing he may not only cure disease in himself and others, but also practically do away with fear and worry and the baser emotions. To teach these things is the object of this work. We will give in a few chapters concise explanations and instructions, which might be extended into volumes. We hope to awaken the minds of the Western world to the value of the Yogi "Science of Breath".