On the morning of July 22, 2020, the Sierra Club’s executive director, Michael Brune, posted a reflection on his organization’s 128-year history. “As defenders of Black life pull down Confederate monuments across the country,” he wrote, “we must also take this moment to reexamine our past and our substantial role in perpetuating white supremacy.”

Brune’s reexamination began with John Muir—the inveterate hiker and activist who founded the Sierra Club and was famous for his eloquent tributes to the Sierra Nevada, many of which were first published in The Atlantic. Though Muir is a renowned figure in the conservation movement, Brune wrote, he made derogatory statements about Black and Indigenous people that drew on racist stereotypes. He maintained friendships with other prominent conservationists well known for their racist beliefs. These and other long-ago words and actions, Brune argued, not only continue to alienate potential Sierra Club supporters but sustain a “dangerous idea” within the organization: “that exploring, enjoying, and protecting the outdoors can be separated from human affairs.”

Many within the Sierra Club applauded Brune’s statement. Michael Horn, a professor at California State University at Fullerton, wrote that although he had supported the Sierra Club as a member for most of the past 35 years, “as a Native American ecologist, I’ve often cringed while doing so.” Brune’s words, Horn added, were a first step toward meaningful organizational change: “Now the real work of the Sierra Club begins.”

Yet many others accused Brune of unfairly applying a “purity test” to Muir, or of “smearing a great individual via guilt by association.” The science-fiction novelist Kim Stanley Robinson, a Sierra Club member and lifelong Sierra Nevada hiker, responded to Brune’s statement by declaring that Muir was not a racist, and that “indeed in the context of his time, he was a tolerant and generous figure, worthy of respect both then and now.”

In a narrow sense, Robinson is right: Muir’s generosity toward and reverence for the members of other species was remarkable, for his time and for ours. But his failures of imagination about the human species were both significant and all too common among conservationists of his time. And as Brune noted, their influence persists, and the resulting pessimism about humans’ capacity to contribute to conservation undermines the work of the Sierra Club and like-minded organizations worldwide. In reexamining the limitations of its icons, the conservation movement has a chance to broaden its own vision.