The knees press the earth, the head the sky. The lower back is stretched and erect, the head is straight on the shoulders, which fall naturally, as does the gaze. And the breathing: the exhalation is deep and long, the inhalation is short and vital. If you can manage to concentrate on, say, the position of the thumbs, or on the exhalation of air, for any length of time – and all of this while thinking-not-thinking