As guide one day for the wife of a well-known geologist, I secured a new idea regarding altitude. We were to spend the day above timberline, where we hoped to identify the distant mountain ranges, observe the wild life close at hand and collect flower specimens. We left the valley at dawn, let our horses pick their way slowly upward. We halted occasionally to watch a scampering chipmunk or to explain our harmless errand to a scolding squirrel. Near the timberline we emerged into a little grassy glade beside a rushing stream. Far above and deep below us grew a dense forest of Engelmann spruce. In the glade stood a detached grove of perhaps a dozen trees, dead and stripped almost bare of limbs and bark. My lady stopped abruptly and stared at these. She shook her head sadly, murmuring to herself. At last she spoke: "Isn't it too bad?" she grieved. I agreed sympathetically, then peered about to learn the cause of our sudden sadness. The lady pointed to the dead trees, wagged her head, and said: "Isn't it too bad the altitude killed them?" There were green trees a mile farther up the mountain above the dead ones in the glade. Yet my lady insisted that the altitude had singled out and killed the little grove in the midst of the forest--so we let it go at that. Of course, some persons really are affected by altitude, but weariness, lack of muscular as well as mental control, often creates altitudinous illusion. Of this condition I had an example while guiding a party of three women and one man to the top of Long's Peak. We climbed above timberline, headed through Storm Pass, and finally reached Keyhole without a single incident to mar the perfect day. The ladies were new, but plucky, climbers; the man rather blustery, but harmless. Beyond Keyhole lies rough going, smooth, sloping rocks and the "Trough" with its endless rock-slides that move like giant treadmills beneath the climber's feet. The pace I set was very slow. The man wanted to go faster, but I called attention to Glacier Gorge below, the color of the lakes in the cañon, in short, employed many tactics to divert him from his purpose. My refusal to travel faster excited him, he became extremely nervous and made slighting remarks regarding my guiding ability that ruffled me and embarrassed the ladies. Hoping to convince him of his error, I speeded up. He remonstrated at once, but when I slowed down to our customary pace he still objected, saying we'd never reach the top before dark. Suddenly he developed a new notion. Climbing out upon a ledge he lifted his arms and poised, as though to dive off the cliff. "Guide," he called, his voice breaking, "I must jump."