We will concern ourselves mainly with Raja Yoga, a system which has been found to be most applicable to the mental and physical conditions in which we live. Raja Yoga has eight principles. These are: (1) Yamanon-killing, truthfulness, non-stealing, continence, and non-receiving of any gifts; (2) Niyamacleanliness, contentment, mortification, study and self-surrender to good; (3) Asanaposture; (4) Pranayamacontrol of vital body forces; (5) Pratyaharaintrospection; (6) Dharanaconcentration; (7) Dhyanameditation; (8) Samadhisuper-consciousness. Yama and Niyama constitute the moral training without which no practice of Yoga will succeed. As this moral code becomes established, the practice of Yoga will begin to be fruitful. The Yogi must not think of injuring either man or animal through thought, word or deed. However, this should not be extended to the limits to which the Jains of India carry it. Their creed forbids them to kill even an insect, and many never bathe lest by placing their bodies in water they may drown some creature living upon them. Yoga is logical. Its principles are not rules of magic that must be followed You will discover later that in the carrying out of these physiological matters there will be a good deal of action going on in the body. Nerve currents will have to be displaced and given new channels. New vibrations will begin and the constitution will in effect be remodeled. The main part of the action will lie along the spinal column, so that it is necessary to hold the spinal column free by sitting erect and holding the chest, head and neck in a straight line. Let the whole weight of the body be supported by the ribs and in an easy natural posture with the spine straight. You will find that you cannot think high thoughts with the chest in. Such is the effect on the body of what we call the mind. After you have learned to have a firm, erect seat, you should perform a practice called the purification of the nerves. In the words of one of the ancient scriptures, or Upanishads, "the mind whose dross has been cleared away by pranayama becomes fixed in the path of Yoga ... first the nerves are to be purified, then comes the power to practice pranayama." Pranayama may seem at first to be totally involved with breathing. However, breathing is only one of the many exercises through which we get to the real pranayama, or control of the prana. According to old Indian philosophers, the universe is composed of two materials, one of which is called akasa, the omnipresent, all-penetrating existence. Everything that has form, or that is made up of compounds, evolves from the akasa. The akasa becomes air, liquids, solids, the sun, moon, stars and comets. It is the akasa that forms animal and plant life. It is everything we see, all that can be sensed and everything that exists. It cannot be perceived, as it is so subtle that it is beyond all human perception. It can be seen only when it has become gross and taken form. At the beginning of creation there was only this akasa, at the end of the cycle, solids, liquids and gases melt into the akasa again, and the next creation evolves from the akasa. The akasa is manufactured into our universe by the power of prana. Just as akasa is the infinite omnipresent material of our universe, so is prana the infinite, omnipresent