No mortar, no nails, nothing to hold his creations together except gravity, an invisible glue he can sense in the stones' "conversations" of squeaks and rumbles. A hollow sound means a void needs to be filled; a solid fit is secured with the sound of a bolt being thrown. Snow's evocative prose and Peter Mauss's richly textured photographs of Snow's work reveal the nuance and beauty of walling--and of one man's relationship with nature. The result is by turns poetic and practical.