I have not given in the previous paragraph about the sighting points for the eyes during meditation a fifth exercise although it is also used among some of the raja yogis and hatha yogis. This is to squint the eyes, producing the well-known cross-eyed effect. I did not give it because it has risks attending it just as the holding of the breath and the alternation of the breath had risks attending them. The risk is to become permanently squint-eyed or cross-eyed if the exercise is overdone either for too long a time at each session or for too many sessions. All these sighting exercises are intended to help, first, the practice of concentration, and second, the further advance into self-absorption or withdrawal from the senses. "And the third purpose is to stop the flowing currents of thoughts." The safest exercise of the five is undoubtedly the Chinese one which I gave as number four. There are no risks attending to that one.
-- Notebooks Category 4: Elementary Meditation > Chapter 2 : Place and Condition > # 239
