Back in the summer of 1977, John Schaefer would sometimes slip out of his Tucson office in the middle of the workday, drive the dozen-odd miles to Mission San Xavier del Bac and spend a couple of hours photographing the lovely 18th century church. Some evenings, he would return after dark, use the key that the parish priest had remarkably entrusted to him, set up his lights and 4x5 view camera inside, and spend several more hours photographing the church’s astounding congress of carved saints and angels.