JOHN Muir is a man I would have loved to have met on the trail. I would have enjoyed walking with him through Tuolumne Meadows in his beloved Yosemite, listening to him discuss each wildflower by name; tell stories of each peak he climbed and the weather on that day; what he saw and how he felt. I wonder if he would have ranted and raved or kindly addressed and advocated for these wildlands in his lifelong pursuit to protect them.

He might have said as he did in his essay The Wild Parks and Forest Reservations of the West, published in his book, Our National Parks: ‘‘Thousands of tired, nerve-shaken, overcivilized people are beginning to find out that going to the mountains is going home; that wildness is a necessity; and that mountain parks and reservations are useful not only as fountains of timber and irrigating rivers, but as fountains of life.’’ And I would have agreed with him. I like to imagine that he could walk with me now in the red rock desert of the Colorado Plateau where Utah, Colorado, New Mexico, and Arizona share a common boundary point in what is known as the Four Corners.

We would stand on the south rim of the Grand Canyon in shared awe, where he once stood and proclaimed that it was: ‘‘as if you had found it after death, on some other star; so incomparably lovely and grand and supreme is it above all the other canyons in our fire-moulded, earthquake-shaken, rain-washed, wave-washed, river and glacier-sculptured world.’’ We might have discussed a wild life versus a domesticated one, and he would have exclaimed, ‘‘I have been too long wild’’ without any thought of changing his passionate stance toward the virtues of a life lived outside.

And then, I would have asked him to visit Big Flats outside of Moab, Utah, now a series of oil and gas drilling sites that look like monstrous, mechanical ravens with their heads rising up and down as they peck on carrion in the red sand on the edge of Canyonlands National Park, which now feels like an annex for the fossil fuel industry.

He might have expressed a longing for a reprieve in the cool alpine air of the Flathead Reserve, now Glacier National Park in Montana, where he said: ‘‘Give a month at least to this precious reserve. The time will not be taken from the sum of your life. Instead of shortening, it will indefinitely lengthen it and make you truly immortal.’’ And I would have had to describe to him that out of the some 150 glaciers visible during the 76 years of his life, a century after he’d left this Earth, only 25 remain, and that glaciologists now predict they will be gone in 15 years.

I would sit down with Mr Muir in the shade of a juniper tree and speak of our warming planet, warming from an increased use of carbon through our excesses of driving cars, travelling by plane, and our societal and global dependence on coal, oil, and all manner of fossil fuels. We would speak of a population of billions and rising.

Perhaps he would enquire about water, being the citizen scientist he was, forever curious, always two steps ahead mentally, and say something to the effect of: “oil is optional, water is not,’’ as the photographer Edward Burtynsky recently said after having spent a lifetime taking pictures of mined and spent landscapes, where toxins fan out at a river’s delta like a blood red hand on the planet.

And then, I can envision we would time-travel back to Yosemite Valley during the days that Congress shut down the government, from October 1 to 16, 2013, because they could not agree on how to fund our national debt. During this dispute, our national parks were closed to the public. The lands rested. The deer and bears and hawks returned momentarily to the uncommon quiet of wild nature and to savour the silences. But the resourceful Muir would have found a way in, and we would have walked quietly, joyously up the trail to Vernal Falls and baptize ourselves once again into the Church of Awe and cleanse ourselves momentarily of grief.

We would have sat very near the falls, wet from the ecstatic spray, and he would have recounted the time when he watched the moon through the veil of water as he braved his own annihilation just for the experience of standing behind the vertical torrent. Neither one of us would be able to tell if our tears were of joy or sadness, both of us knowing they spring from the same source: a love of beauty and all things wild.

What I would ask John Muir at that tender moment is: “When you wrote ‘John Muir–Earth–Planet–Universe’ inside the cover of your notebook, how did you know we were made of stardust? How did you understand a planetary consciousness when 100 years later we are just beginning to comprehend your prescient words, ‘When we try to pick out anything by itself, we find it hitched to everything else in the Universe’?’’ Donald Worster, the historian and author of A Passion for Nature: The Life of John Muir, sees the Scottish-born naturalist’s legacy as a spiritual one. At a forum about Muir at Stanford University he said: “We should think about John Muir as the inventor of a new American religion. I don’t mean to put America in there exclusively, because people all over the world have responded to him . . .

“I think he is a religious prophet, and a lot of people in this country have followed him or followed those ideas ... He’s important for the great work he did for getting our national parks and forests and wildlife refuges and wild places and beauty in our consciousness and concerned about saving them. I think he’s also important . . . as a kind of measuring stick for understanding where we were as a people and where we ought to be today . . .”

Consider me one of Muir’s followers, even disciples, of his wild joy, walking behind him on the path of wilderness protection. I am grateful that Everyman’s Library has chosen to publish this John Muir Reader in the nick of time.

This is an extract from Terry Tempest Williams’s introduction to Selected Writings by John Muir, which is published by Everyman’s Library at £14.99 and out now. Find out more here.