Hatha yoga aims to allow a number of practices called kriyas, which are intended to help cleanse the body and balance the three bodily humors (doshas), ensuring good health. Two classical books on Hatha yoga, the Hatha Yoga Pradipika and the Gheranda Samhita, describe six kriyas. Four of these: Skull Shining Breath (page 327), Candle Gazing (page 344), Saline Nasal Irrigation (page 346), Abdominal Churning (page 348)—are described in this book and are safe to learn without a teacher. The two remaining practices require personal instruction. They are dhauti, the practice of cleansing the stomach with water or with a thin strip of cloth, and vasti (or basti), the practice of washing the large intestine using either water or air.
