The hellish pace set by Iverson was a godsend. Traversing the rugged subterranean landscape took all of Anna's concentration and all of her skills. The interior of the planet did not seem governed by the same laws of physics as its exterior. Or perhaps it was just that the route was non-negotiable. One couldn't pick and choose passes or climbs; one went where there was no dirt in the way.

Such were the demands of travel that majesty and grandeur were lost. Anna wasn't sorry. Hard physical work was a balm for her soul. Vast slopes of scree were painstakingly descended. Boxcars of stone, upended and angled in a hundred ways, stacked against each other until they formed smaller passages of their own. Hands were used like an extra pair of feet for balance. Chunks of stone slid underfoot, and ankle-breaking traps opened between rocks the size and stability of bowling balls.

Names went by with the black velvet-clad scenery: Colorado Room, seen as a series of slides framed by the limiting scope of headlamps; Glacier Bay, great pale glaciers calving in a sea of night. Windy City, Rim City.

Anna used her body in a way she seldom had since childhood. Though occasionally alarmed at being called out of an early and long retirement, her muscles gloried in the exercise. As she bent and stretched, hopped from boulder to boulder in faltering and moveable light, slid down talus slopes on butt and heels, hauled herself up rocks, scrabbling with fingers and toes for purchase, it came home to her how stultifying the dignified world of grown-ups had allowed itself to become. How limiting and unsatisfying to deny our simian ancestry by walking always upright and sitting in chairs, throwing away natural powers for some inherited code of decorum.