The horses headed what appeared almost a perpendicular wall. Donnie saw Fox stretch his body like a greyhound and fairly hurl himself in leaps at the steep incline, scattering stones in every direction. Pet stood a moment, undecided, then with a shrill whinny started after Fox. Donnie grasped the horn of the saddle and clung to it desperately, leaning forward and shutting his eyes. His back jerked, his head wouldn't keep still, his heart beat violently. "If Pet would only keep still a minute," thought the child. "Suppose Fox were to fall with Marmee, what would I do?" He pulled on the reins, but Pet, watching Fox, fought the bit, and lunged ahead. As if in answer to Donnie's thoughts, his mother's voice drifted cheerily back to him: "Almost there, dear. Tired?" "Just a little bit," he replied, trying to be brave, but wishing he could ride up beside her and hold her hand a minute. Then he remembered Galahad had ridden alone, and knights were not afraid of anything. He pretended that the trail led to the castle of an enemy and he was going to rescue those held prisoners, so with bolstered courage, he kept his eyes open and fixed on the horse ahead of him. They reached a sharp knoll that formed the apex of the mountain; and after slipping from the ponies and tying them to a stunted bit of scrub oak, Katherine clasped Donnie's hand in her own, and together they approached the edge of the cliff, and peered cautiously over. Two thousand feet below was the canyon, but where they gazed, four solid walls arose like a gigantic box without a cover. There was no entrance or exit. The Mexicans called the place El Cajon, or the Box. Grass, flowers, trees and a trickling stream from a spring lay at the bottom of the Box, but nothing living could reach there. The walls were as straight and sheer as the name of the place implied. They drew back from inspecting it, and at Katherine's suggestion Donnie gathered wild flowers to decorate the table on which she spread the lunch. The mother made a pretense at eating, but the memory of the impending separation thrust itself on her despite her determination to forget it this one day. Neither she nor Glendon had told the child, so no shadow of tragedy spoiled his enjoyment. The ride had tired him, and after lunch was over, she arranged the Navajo blankets. He stretched out lazily, watching his mother draw his favourite book from her saddlebag. Then he curled up with a sigh of ecstasy. "Where shall I read?" she asked, smiling down at him. "How Sir Galahad was made a knight," he answered, "and about the Siege Perilous." So she read until the brown head nodded and the eyes closed slowly, then seeing the boy slept, she laid the book aside, sitting motionless and watching him with miserable eyes.