Cat Jarman led me through a dense tangle of forest called Heath Wood. We were in Derbyshire, close to the very heart of England. There was no path, and the forest floor was overgrown with bracken and bush. It was easy to lose your footing and even easier to lose your way. Jarman, a fit, cheery woman in her late 30s, plunged jauntily on as I tried to keep up. “See all these lumps and bumps?” she asked as we broke into a small clearing. She pointed to an array of 59 small, rounded hillocks, many two or so feet high and four or five feet in diameter. Humans, not nature, had clearly put these things here, and they gave off a spooky, supernatural energy.