"A rock pile ceases to be a rock pile the moment a single man contemplates it, bearing within him the image of a cathedral." -Antoine de Saint-Exupery.
Stacking Stones is a zen like experience. You must remain focused and in tune with the materials at such a close level that the rest of the world sort of melts away. I walk along this stretch regularly and pause on most days to build a tower or two. It helps me to relax and get back in touch with the hear and now.