The whole urgency here is a movement upward through the body, off the flat ground of appetite toward the raised place in the skull where awareness rises above the senses. To look behind is to keep the attention fixed on the burning cities of the lower nature, and to stay clenched there is to be dissolved back into them. The plain lies level with the flesh, where nothing lifts.
What happens in a person is a turning of the inner gaze forward and up, away from the smoking wreckage of old cravings toward the summit where thought becomes light. Attention held on the ruined lower life is ruined with it; attention drawn to the crown survives.
Mountain: the crown of the head, the high inner place where consciousness rises out of the reach of the senses
Plain: the flat ground of the flesh and its appetites, level ground where awareness never lifts