It’s midday in northern New Mexico, and the guided tour starts with a request (nay command) to stay on the sandy path. We’ve come to visit a cave: in 1994, local cave digger Ra Paulette (he shirks the term artist) began burrowing into a sandstone cliff to create the intricate interiors of Windows on the Earth, a sanctuary-like hideaway. Dug by hand over the course of two years, it comprises a sequence of tall and narrow vaults converging on a central space, where a throne-like seat is set high up in the wall; as you move through the cave, eccentric ornamentation — organic whorls, fossil-like seashells, shrine alcoves — punctuates implausibly smooth surfaces. It’s a wonder of man shaping the landscape, but first, we’ve stopped for a New Age biology lesson.