Noah (one of Philly's new teachers) talked about the whole point of the ashtanga yoga practice: to quiet the mind.
He explained that our mind is like a lake, our never-ending thoughts are ripples in the lake, and we see and interpret the world through these ripples. The purpose of the ashtanga practice is to clear the ripples so we can see the true reflection.
He talked about the three ways this occurs through the ashtanga practice:
1. Breathing. Slow, conscious breathing through the nose.
2. Gaze (dristi). Our mind follows our eyes so we must control our gaze. Gaze should be at the nose (most of the time), or third eye, toes, thumbs. It should not wandering around the room or looking in the mirror.
3. Physical postures (asana). The word “asana” is translated to “chair.” Asana is the chair from which we practice breath and gaze in order to quiet the mind.
I like this explanation because it takes the emphasis away from the physical yoga postures, and focuses it on the larger purpose of the practice which is to quiet the mind, and the physical postures are just a tool to get there.