There is no man-made trail, only a deer path, a bighorn-sheep path, a lion run, leading to the spring. The stones are loose and tricky, the drop-offs vertical, the brush and cactus thick, resistant, hostile. One proceeds with care. A broken leg could be a serious mistake, especially when alone. Accidents are forbidden. But the birds like it here: I was serenaded on my way by the sharp whistles of a thrasher—that signal so humanlike that the first few times you hear it you always stop and look around, expecting to see a boy or another man. Or a woman, now that women have liberated themselves from certain genteel constraints. (“Whistling girls and crowing hens,” my grandmother used to say, “both shall come to no good ends.”)

Other birds are also present. I heard a cactus wren, its voice like the chatter of a rusty adding machine. And the sweet brief tunes of cardinal, pyrrhuloxia, phainopepla—the last a shy and furtive little bird, hard to get to know.

I reached a saddle in the mountains without finding the spring, though the convergence of tracks left by many small feet suggested that I was getting close. Plus the variety of scat on the trail: not only bighorn sheep and deer but also coyote, rabbit, kit fox and the messy little clots of dung of the javelina, the wild pig or peccary of the southwestern deserts.

Once on the other side of the saddle and around a few more overhangs of rotten volcanic rock and through a tunnel in the thorny mesquite and catclaw acacia, where I crawled on hands and knees to save the shirt from being torn off my back, I found the spring. It was easy to spot: a clump of leafless but conspicuously coppery willows, a dwarf cottonwood barely beginning to leaf out with the soft green of a new growing season. The little trees made only a patch of deciduous life in the midst of many square miles of blue stone and olive-drab desert growth, but that single tiny patch was sufficient to indicate the presence of the desert’s sweetest miracle—surface water. Or at the least, water very close to the surface. About fifty yards short of the spring and a little above it, downwind from the prevailing westerlies, I came upon a blind of saguaro ribs. I squatted down in the lattice shade of the thing armed with binoculars, notebook, a canteen of water, a hunk of longhorn cheese, a box of raisins, and I waited.

The sun went down. I put on my coat as the temperature dropped ten, fifteen, twenty degrees within twenty minutes. Binoculars ready, I watched the water hole—the only water hole within twenty miles. The bird songs faded away. Crickets began to rub their fore wings together down by the spring. The lavender dusk, in a precipitation of colors too subtle to name, spread across the desert hills, through the sky, across Sonora to the south, across the fifty miles of landscape within my range of sight. The sickle of moon grew brighter.