As I discovered the larger wisdom tradition of yoga, I was intrigued: The practitioners of this science of extraordinary living have lived and thrived on the Indian subcontinent for at least the last three millennia. They have concerned themselves with a series of perennial questions — questions that are as challenging today as they were when scantily clad yogis first gathered in the forests and mountains of India: What is an optimal human life? What would it be like to function at the maximum potential or our minds and bodies? . . .

These yogis, too, have been interested in a second, related series of questions: What are the root sources of human suffering? Can these roots of suffering be cut? Can human beings learn to be happy and at ease in this difficult life?

Their answers to this second set of questions have also been surprising — and, frankly, for many Westerners, just plain unbelievable. Yogis studied the structure of ordinary human unhappiness, and found that the sources of everyday suffering could be entirely "extinguished" — leading to a kind of freedom we ordinarily think impossible. Yogis have called this "liberation." Liberation in this instance means freedom from all the sources of conditioning that bind us to small ways of thinking and being. Liberation means being entirely awake, and fully alive.

Stephen Cope in The Wisdom of Yoga