John Muir led an adventurous life, starting with his wild and playful boyhood in Scotland to his legendary exploits in America, where he became an inventor, a global explorer, and the first modern environmentalist—and even became friends with a president! His heart was always in the outdoors and he aimed to experience all he could. Most importantly, though, John Muir told the world about the wonders of nature. His words made a difference and inspired people in many countries to start protecting planet Earth— and they still do.