It Is All in the Allowing, not the Physiology

What does it mean to allow? For me that question is the beginning and the end of practice. Nishijima Roshi goes on and on about balance of the autonomic nervous system. Physiological balance must be a vital part of what is allowed to happen in Zazen. But to focus too much on that, it seems to me, might be a kind of mistaking the finger for the moon. The essence of the practice is not in the physiology but in the allowing.