Few modern poets are as easily quotable (and indeed as widely cited) as Mary Oliver, the late Pulitzer winner whose elegant but simple reflections on the natural world have been taken seriously by millions of people as mantras for a calmer, more conscious way of life. Depending on who you talk to, that’s a testament to the brilliance or banality of his work. There are very few poets who have the privilege of becoming very popular during their lifetime, but that profile is often accompanied by rejection from certain corners of the literary world: the suspicion that any verse understood by so many people cannot be so profound. An appropriately accessible and candid documentary about her life and legacy, Sasha Waters’ “Mary Oliver: Saved by the Beauty of the World” does not address such criticisms on an academic level; he prefers to respond with the emotional power of Oliver’s own words.

He does this from the beginning, beginning with one of Oliver’s many famous fans, Stephen Colbert, attempting to recite his best-known poem, “The Summer Day.” Long before he reaches his famous final lines (“Tell me, what do you plan to do / with your one precious life?”), he falters, overcome with tearful sentiment. He is not the first person to be created. verklempt for a poem that has become a staple at both weddings and funeral services: it is the most crystalline example of Oliver’s ability to overlay seemingly anodyne everyday images, usually drawn from nature, with probing existential implications.

However, when reduced to decontextualized fragments, Oliver’s words can sound simple or epigrammatic in ways that do not necessarily reflect his philosophy; Just look at how many times his phrase “joy is not meant to be a crumb” has been used and abused by food marketers and culinary influencers. Such are the dangers of popularity, all the more ironic since Oliver never intended to be a populist. A reserved and reticent person, protective of her queer identity and relationships, she wrote for herself, inspired by her constant and sustaining love of the outdoors: “Looking at the world, whatever situation my finances were in, was the important part of my life,” she says in an excerpt from an archival interview.

Waters’s film tells the story of Oliver’s life from a respectful distance, without seeking unprecedented intimate knowledge of the subject, which is just as well, since the loved ones and associates interviewed here have no interest in betraying his trust. “If I thought of something she didn’t want me to tell you, I wouldn’t tell you,” says the most surprising and entertaining of the film’s talking heads: filmmaker John Waters (no relation to this film’s director), who we learn became close to Oliver and his partner, photographer Molly Malone Cook, when they were almost neighbors in Provincetown, Massachusetts. An equally unlikely friend, Maria Shriver, is equally guarded: “I really protect my conversations with Mary,” she says.

Still, aided by archival photographs and video, a moving picture emerges of a life lived strictly on Oliver’s own terms: Once a lonely child, she found companionship not only in like-minded artists and social outsiders, but also in the flora and fauna that were equally important to her personal ecosystem. John Waters, understated but still a rich source of anecdotes and human knowledge, helps ground and demystify a woman sometimes popularly labeled with an earth mother spiritual aura, whether informing us of her chain-smoking habit or jokingly recounting the time she was bitten by a badger. Oliver may have lived his own world to a certain extent, but that world was still the real one.

Meanwhile, luminaries ranging from Oprah Winfrey to Steve Buscemi, V (the author and playwright formerly known as Eve Ensler), and other American poets such as Major Jackson and Ada Limón, are on hand to pay more glowing tributes to Oliver’s work, detailing what it has meant to them and to the culture at large.

The diversity of voices brought together is an apt reflection of the scope and impact of the subject, and while a more provocative film might have included more skeptics or critics (perhaps one that explains why, as noted here incredulously, Oliver never received a full review in the New York Times), Waters’s documentary is unashamedly celebratory, and persuasive as such. It is sure to delight a large number of the poet’s fans when it airs on PBS in late August, following a limited theatrical run beginning this weekend. (It premiered as the opening film of the True/False documentary festival in March.) Meanwhile, about its subject, “Mary Oliver: Saved by the Beauty of the World” provides enough color and context to prompt viewers to return to the poems themselves, to search for the writer in words that so many readers have claimed for themselves.