My borrowed tour guide, in describing the carefully crafted bas-reliefs on the walls of the Angkor temples, explains that the oils in human hands can alter and even stain the coloration of the sandstone from which the temples are carved. Above, we can see where people have decided to "get a good feel" for the temples over the centuries. I'm not sure how to say "Amen" in Khmer, so just... amen.
