It is a shuddhikriya meant for cleansing the eyes and for making the' mind silent in concentration.
Sitting with a straight back, the eyes are fixed on an object without winking until tears start rolling down the cheeks. And small object like the flame of an oil lamp, or an image, or picture, or the letter 'AUM', would do. The object should be placed in line with the eyes at a distance of four to six feet. Perhaps the best thing is not to have any particular object at all to look at. One should just stare in front at the wall without moving the eye-balls or the eyelids. Before doing trataka one may go through movements of the eyes without moving the head in which the eye-balls are rolled up and down, sideways, and from corner to corner diagonally, repeating each movement four to six times. First these movements should be made with open eyes and then with the eye-lids closed. This gives exercise to the eye muscles. It should be followed by Trataka. Trataka is said to make the eyes clear, improve sight, and remove eye troubles. It makes the everwandering mind silent.BastiIt is a shuddhlkriya for c1eansing the colon. Its action is like enema. One cannot do Bastl unless one knows how to practise Nauli. A rubber tube about nine inches in length and with an inner passage as wide as to allow the little finger to enter it, is necessary for doing Basti. Taking about a litre of clean water in a bowl, one sits in Utkatasana, and inserts one end of the cleaned and lubricated tube into the anus, passing about four inches length of the tube inside. Then dipping the other end into the bowl, Nauli is done, which creates vacuum in the abdominal cavity, thereby sucking Some water into the colon. Now the end of the tube is closed with the tip of a finger, and after relaxing the abdominal muscles for a while, Nauli is done again, at the same time removing the finger from the end of the tube. This allows some more water to rush into the colon. The procedure is repeated a third time. Then the tube is removed from the anus and the bowels are evacuated. So Basti is best done in a toilet.Basti is better than enema in that it allows water to reach upto the ceacum, i.e., the beginning of the large intestine and cleans the colon very effectively.
