The highest achievement of the yoga of body control which is effected through certain breathing exercises is the state of utter unconsciousness of the physical body and of the physical world. Although this also effectively stops the process of generating thoughts, its result must not be confused with that stoppage which is attained in the intermediate or advanced mystic exercises. It is quite true to say that before or during the deep-trance state to which these breathing exercises eventually lead, the yogi's body can show remarkable powers; it may be buried under ground for hours or even days and emerge unharmed; it may be stabbed with knives but suffer hardly any loss of blood; its heart and lung action may cease entirely so far as finger and stethoscope tests may be able to ascertain; and corrosive poisonous acids may be poured into its stomach without hurting its membranous lining.
-- Notebooks Category 5: The Body > Chapter 6 : Breathing Exercises > # 26
