“Understandably enough, they [the Paleolithic people] would have believed that caves led into [a] subterranean tier of the cosmos. The walls, ceilings, and floors of the caves were therefore little more than a thin membrane between themselves and the creatures and happenings of the underworld. . . .

[It] was the act of covering the hand and the immediately adjacent surfaces with (usually red but sometimes black) paint that was important. People were sealing their own or others hands into the walls, causing them to disappear beneath what was probably a spiritually powerful and ritually prepared substance, rather than “paint” in our sense of the word. The moments when the hands were “invisible,” rather than the prints that were left behind were what mattered most. . . . [T]he hands thus reached into the spiritual realm behind the membrane of the rock, though in this case paint acted as a solvent that dissolved the rock.”

—Jean Clotte, from The Shamans of Prehistory: Trance and Magic in the Painted Caves, 1998; quoted by Gregory Curtis in The Cave Painters: Probing the Mysteries of the World’s First Artists, 2006.