During the course of practice, one day you will feel that you have separated yourself from the body. You will have immense joy mixed with fear; joy in the possession of a new light, astral body; and fear owing to the entry in a foreign, unknown plane. At the very outset, the new consciousness is very rudimentary in the new plane. You will only feel that you have a light, airy body and will perceive a rotating, vibrating, limited astral atmosphere with illumination of golden lights, objects and beings. You may feel that you are floating in the air.
You will never fall; but the new experience of subtlety generates novel feelings and sensations in the beginning. How you leave the body and remain, is unknown. You are unaware of how you have completely separated yourself from the body. The new joy is inexpressible. Your will have to actually feel and experience it yourself. When you come back to body-consciousness, there is an intense craving to regain the new consciousness and to remain in that state always. By chance, by repeated attempts, you are able to go beyond the body-consciousness once in a month or so in the course of Sadhana. If you plod on with patience, through Yogic practices, you will be able to leave the body at will and stay for a long time.
You can by mere willing travel in any place you like with the astral body and there materialise by drawing the necessary materials either from Ahamkara or the universal storehouse. The process is very simple to occultists and Yogis who know the rationale, the detailed technique of the various operations. Thought-reading, thought-transference, psychic healing, distant healing, etc., can be very easily performed by those who can function with the astral body. Concentrated mental rays can penetrate opaque walls and travel miles and miles.
Excerpted from Kundalini Yoga by Sri Swami Sivananda, A Divine Life Society publication.