Yoga is, in part, about balance. Physical activity stands in, as does much in the practice of yoga, for an emotional and psychological action. When you begin to feel solidly placed while standing with one foot off the ground, you start to develop a pattern of thought that helps you to feel grounded with one metaphorical foot off the ground.

One of my favorite balancing poses to teach is Vrksasana (pronounced vrik-shah-sahnah) or Tree Pose. (But look toward the horizon, please, not up.) It is accessible to most students, especially if they let themselves start out by standing with one side against a wall, so that when balance becomes shaky, they can connect with some support.

The posture is done by first feeling one foot really connected to the floor. I have my students start by raising the toes and pressing down into the heel, then lifting the heel and pressing the ball of the foot against the floor, then rolling to the inside edge of the sole, then the outside edge. Then, I instruct them to feel all four corners of the foot simultaneously - as though the foot is suction cupped to the ground. Next, they bring one foot against the lower calf or the upper thigh. Hands come to the heart, and now the really interesting part of the pose begins. Because in order to reach up, you need to reach down into the feet. And in order to balance, you need to allow the ankle to wobble -- and then react to that wobbling by reinstating balance.

This is what I love about the pose: it allows us to experience the fact that balance comes not by finding a state of equanimity and sticking there forever - but by reacting, moment by moment, breath by breath, to change. And by illustrating that progress - represented in Vrksasana by the ability to lift the crown of the head, straighten the spine, and bring the arms over the head with the palms against each other - not by reaching forward, but by grounding, reaching in the opposite direction of down, into the feet, versus up, into the air. It tells us that growth is a process like that of a garden growing: the seed has to reach down, set roots, in order to reach up into the air and develop. Hmmm. All this in one little yoga pose.

I've been reading an amazing book called Balance by Scott McCredie, that says far more about the incredible systems within us that keep us balanced throughout our lives. We have three different processes - vestibular balance, situated in the ear canals, which tells us how our head is oriented in relation to the world around us; vision; and proprioception, or cells within muscles and joints that tell us where one part of the body is in relation to another. McCredie explains these systems in layman's terms and gives some intriguing examples, including why humans love rocking chairs; why JFK Jr.'s plane went down while he was flying at night; and how balance helped the Homo sapiens survive while the clumsy Neanderthals became extinct. And he argues, very convincingly, that balance is a sixth sense which we must practice as often as possible to avoid the falls that incapacitate so many elderly people.

McCredie says that we are like large triangles balanced on one little point - our feet. Imagine a large football player or a Sumo wrestler, and consider how surprising it is that these athletes can dance about with all that mass poised above a small platform against the earth. At the end of the book, he gives several exercises to do to practice balance.

Or, you could take a yoga class and see how it changes your sense of balance. Let the ankle wobble. That's what it is designed to do; it is made up of several small bones that allow us to shift and reorient in relation to gravity, change, our breath. And then notice that still feeling within, at the center of the pose, where you find a moment of no wobble, no activity, but balance, even for just a second of time.