Accoring to the traditional teachings of Yoga and various esoteric, occult, and mystical teachings, human beings are constituted not only by a gross physical form but by a series of energetic psycho-spiritual subtle bodies each of increasing subtlety and metaphysical significance. Derived principally from the Indian spiritual tradition where they were originally conceived as sheaths covering the immortal soul these concepts spread throughout the West in the late nineteenth century through the theosophical movement.