He so loved trees that he once climbed a pine during a particularly bad storm just to see what it was like to be a tree in heavy winds. In the April 1900 issue, he described Yosemite’s trees in exhaustive detail, including its sugar pines:

No traveler, whether a tree lover or not, will ever forget his first walk in a sugar-pine forest. The majestic crowns approaching one another make a glorious canopy, through the feathery arches of which the sunbeams pour, silvering the needles and gilding the stately columns and the ground into a scene of enchantment.

It was in that essay that Muir described meeting Ralph Waldo Emerson, a leader of the Transcendentalist movement and prominent writer for The Atlantic, in Yosemite in 1871. After many failed attempts to get Emerson to go “rough camping” with him, Muir said to Emerson, sitting in Mariposa Grove, “You are yourself a sequoia. Stop and get acquainted with your big brethren.” Emerson, however, was “past his prime” and would not join him.

Muir devoted the same loving attention to the flowers of Yosemite as he had lavished on its trees. As he wrote in the August 1900 issue:

In general views of the Park scare a hint is given of its floral wealth. Only by patiently, lovingly sauntering about in it will you discover that it is all more or less flowery, the forests as well as the open spaces, and the mountain tops and rugged slopes around the glaciers as well as the sunny meadows. Even the majestic cañon cliffs, seemingly absolutely flawless for thousands of feet and necessarily doomed to eternal sterility, are cheered with happy flowers on invisible niches and ledges wherever the slightest grip for a root can be found; as if Nature, like an enthusiastic gardener, could not resist the temptation to plant flowers everywhere.

One of his final observations of the national park for The Atlantic came during the April 1901 issue, when he excitedly described Yosemite’s waterways. He recounted one specific location in the park of which he was particularly fond—the north fork of Owens River—which he says had “wonderful champagne water” that was best imbibed by leaning down and drinking directly from its source, “lest the touch of a cup might disturb its celestial flavor.”

A story from that essay captures the joy Muir found there:

In Yosemite Valley, one morning about two o'clock, I was aroused by an earthquake; and though I had never before enjoyed a storm of this sort, the strange, wild thrilling motion and rumbling could not be mistaken, and I ran out of my cabin, near the Sentinel Rock, both glad and frightened, shouting, "A noble earthquake!" feeling sure I was going to learn something.

A boulder soon gave way up the valley, tumbling down, leveling trees, and breaking into piece. After the dust settled and the chaos calmed, he observed:

Nature, usually so deliberate in her operations, then created, as we have seen, a new of features, simply by giving the mountains a shake,—changing not only the high peaks and cliffs, but the streams. As soon as these rock avalanches fell every stream began to sing new songs; for in many places thousands of boulders were hurled into their channels, roughening and half damming them, compelling the waters to surge and roar in rapids where before they were gliding smoothly. Some of the streams were completely dammed, driftwood, leaves, etc., filling the interstices between the boulders, thus giving rise to lakes and level reaches; and these, again, after being gradually filled in, to smooth meadows, through which the streams now silently meander; while at the same time some of the taluses took the places of old meadows and groves. Thus rough places were made smooth, and smooth places rough. But on the whole, by what at first sight seemed pure confusion and ruin, the landscapes were enriched; for gradually every talus, however big the boulders composing it, was covered with groves and gardens, and made a finely proportioned and ornamental base for the sheer cliffs. In this beauty work, every boulder is prepared and measured and put in its place more thoughtfully than are the stones of temples.

In his writings, he explored nature with such reverence that the trees, insects, and animals became characters. He wanted visitors of Yosemite to appreciate their surroundings as much as he did. That became clear in the November 1898 issue, when he wrote:

Travelers in the Sierra forests usually complain of the want of life. “The trees,” they say, “are fine, but the empty stillness is deadly; there are no animals to be seen, no birds. We have not heard a song in all the woods.” And no wonder! They go in large parties with mules and horses; they make a great noise; they are dressed in outlandish unnatural colors; every animal shuns them. Even the frightened pines would run away if they could. But Nature-lovers, devout, silent, open-eyed, looking and listening with love, find no lack of inhabitants in these mountain mansions, and they come to them gladly. Not to mention the large animals or the small insect people, every waterfall has its ouzel and every tree its squirrel or tamias or bird: tiny nuthatch threading the furrows of the bark, sheerily whispering to itself as it deftly pries off loose scales and examines the curled edges of lichens; or Clarke crow or jay examining the cones; or some singer-oriole, tanager, warbler-resting, feeding, attending to domestic affairs. Hawks and eagles sail overhead, grouse walk in happy flocks below, and song sparrows sing in every bed of chaparral. There is no crowding, to be sure. Unlike the low Eastern trees, those of the Sierra in the main forest belt average nearly two hundred feet in height, and of course many birds are required to make much show in them, and many voices to fill them. Nevertheless, the whole range, from foothills to snowy summits, is shaken into song every summer; and though low and thin in winter, the music never ceases.

Muir’s way of looking at America’s national parks may strike the contemporary reader as alien. The president’s visit comes as the National Park Service is beset by internal controversies, and there seem to be weekly incidents of visitors failing to respect what conservationists for over a century have tried to protect. But overall, visits to National Parks have steadily increased, topping 300 million for the first time in 2015. More and more Americans, it seems, may feel as Muir did in 1873: “The mountains are calling and I must go.”