"Yoga is the settling of the mind into silence." The Yoga Sutras of Patanjali
If you notice there is no mention of chatarungas, triangle pose or even close your eyes and say "OM". Often when I meet a new student I'll ask them why they chose yoga and often they'll say they want to learn to relax. One way to do this is to quiet that continual inter- dialogue in our head and most the time that dialogue is a repeat of the same old song. So often we do start the class with a few chants of "OM" to help us settle the mind from those thoughts such as..."I really need to lose five pounds, should I stop by the supermarket after class or maybe the cleaners first, if I stop by the cleaners first I might get caught in the after work traffic on Main Street, then there will be smaller lines if I go the supermarket first, gee I got to lose weight, maybe I don't have to stop by the cleaners today, do they yoga pants make my butt look big , I really need to lose five more pounds..." And the beat goes on. So we start with the sound of OM because you can't hold two thoughts at the same time.