While doing the postures, your mind should be in half-consciousn ess, which does not mean sleep. It means silence, emptiness, space, which can then be filled with an acute awareness of the sensations given by the posture. You watch yourself from inside. It is a full silence.
B.K.S. IyengarI think overall the majority of people who are practicing it as a subject are following the right line. For the aberration, don't blame yoga or the whole community of yogis
B.K.S. Iyengar