Scipio looked across the corral at the gray sky. A slight stiffening of his figure ensued, and he knit his brows. Then he rubbed a hand over his eyes and looked again. “You after sheep?” It was the boy sitting on the corral. We paid him no attention. “It’s about gone,” said Scipio, rubbing his eyes again. “Did you do that to me? Of course y’u didn’t! What did?” I adopted the manner of the professor who lectured on light to me when I was nineteen. “The eye being normal in structure and focus, the color of an after-image of the negative variety is complementary to that of the object causing it. If, for instance, a yellow disk (or lozenge in this case) be attentively observed, the yellow-perceiving elements of the retina become fatigued. Hence, when the mixed rays which constitute white light fall upon that portion of the retina which has thus been fatigued, the rays which produce the sensation of yellow will cause less effect than the other rays for which the eye has not been fatigued. Therefore, white light to an eye fatigued for yellow will appear blue--blue being yellow’s complementary color. Shall I go on?” “Don’t y’u!” Scipio begged. “I’d sooner believe y’u done it to me.” “I can show you sheep.” It was the boy again. We had not noticed him come from the corral to our wagon, by which he now stood. His eyes were now eagerly fixed upon me; as they looked into mine they seemed almost burning with some sort of appeal. “Hello, Timberline!” said Scipio, not at all unkindly. “Still holding your job here? Well, you better stick to it. You’re inclined to drift some.” He touched the horses, and we left the boy standing and looking after us, lonely and baffled. But when a joke was born in Scipio it must out: “Say, Timberline,” he called back, “better insure your clothes. Y’u couldn’t replace ’em.” “I’m no two-bit man,” retorted the boy with anger--that pitiful anger which feels a blow but cannot give one. We drove away along the empty stage-road, with the mountains and the dying storm, in which a piece of setting sun would redly glow and vanish, making our leftward horizon, and to our right the great undulations of a world so large as to seem the universe itself. The air was wet still, and full of the wet sage-brush smell, and the ground was wet, but it could not be so long in this sandy region. Three hours would see us to the next house, unless we camped short of this upon Broke Axle Creek. “Why Timberline?” I asked after several miles. “Well, he came into this country the long, lanky, innocent kid like you saw him, and he’d always get too tall in the legs for his latest pair of pants. They’d be half up to his knees. So we called him that. Guess he’s most forgot his real name.” “What is his real name?” “I’ve quite forgot.” This much talk did for us for two or three miles more. “Must it be yellow?” Scipio asked then. “Red’ll do it, too,” I answered. “Only you see green then, I think. And there are others.”