Every other creature on the face of the Earth knows how to just shut up and sit: a butterfly on a leaf, a cat in front of a fireplace. Even a hummingbird comes to rest sometimes. But humans seem to be constantly on the move all day long. Even during the night we have to dope ourselves just to fall asleep. We seem to have lost the ability of our primitive ancestors to just be still with ourselves. Out of that stillness, our whole life arises.
John Daido Loori, The Eight Gates of Zen: A Program of Zen Training