That which is form is not other than emptiness. That which is emptiness is not other than form.
- Heart Sutra
Yoga is the ability to free the heart and mind by progressive degrees from the contours of consciousness. When this is successful, that source from which all form originates is experienced as it is, and the yogi finds this source within herself. At other times, this source is lost to her and she identifies herself with various aspects of the contours of consciousness.