“I am nothing more than a single, narrow gasping lung, floating over the mists and summits,” the storied Italian alpinist wrote of his seminal solo ascent of Everest without supplemental oxygen in the summer of 1980. Messner had already completed a gas-free ascent, with Peter Haebeler, two years earlier, but this climb symbolized everything that “pure” mountaineering strove for in the modern era: A fully self-supported, alpine-style ascent to the highest point on earth. Few believed it could be done, and it completely altered what high-altitude physiologists understood about human limitations. While commercial climbing and expedition-style tactics remain status quo on Everest and other big peaks, Messner established the gold standard. From that point forward, no reasonable discussion of why mountaineering matters could take place without it.