When we think of a party of climbers struggling along the final ridge of Mount Everest, we are perhaps inclined to reject an obvious comparison of their endeavour with that of athletes in a long distance race. The climbers are not of course competing to reach the goal one before another; the aim is for all to reach it. But the climbers’ performance, like the runners’, will depend on two factors, endurance and pace; and the two have to be considered together. A climber must not only keep on moving upwards if he is to succeed, he must move at a certain minimum pace: a pace that will allow him, having started from a given point, to reach the top and come down in a given time. Further, at a great height it is true for the climber even more than for the runner on a track in England that to acquire pace is the chief difficulty, and still more true that it is the pace which kills. Consequently it is pace more than anything else which becomes the test of fitness on Mount Everest. Every man has his own standard, determined as a result of his experience. He knows perhaps that in the Alps with favourable conditions he is capable of ascending 1,500 feet an hour without unduly exerting himself and without fatigue; if he were to bring into action the whole of his reserves he might be able to double this figure. He will assuredly find when he comes up into Tibet and lives at a mean height of 15,000 feet that he is capable of very much less. And then he begins to call in question his power, to measure himself against his European standard. Every member of both Everest Expeditions was more or less of a valetudinarian. He had his eye on his physical fitness. He wondered each day, Am I getting fitter? Am I as fit as I should expect to be in the Alps? And the ultimate test was pace uphill.