On a crisp spring morning, I trusted a horse — a bay named Sino — to show me the vast Gila Wilderness of southern New Mexico. Red rock walls rose beside us as we wove back and forth across a shallow creek separating ponderosa pine on the shady south side of Rocky Canyon from barrel cactus in the cliff crevasses on the desertlike north face. I leaned against his neck as Sino climbed a steep ridge that led to a hilltop savannah of pinyon, juniper and groves of tentacled cane cholla cactus tipped in faded yellow fruit. Surrounding them, forested mountains were unblemished by buildings or roads.