Crazy as it sounds, it might have been the I Ching that saved the whales.

In 1975, after weeks of fruitlessly trying to track a Russian whaling fleet, the founding members of Greenpeace were about to abort their very first antiwhaling mission when they decided to consult the ancient Book of Changes. As related in the fine documentary How to Change the World, opening Friday (August 7), it was the vast statistical improbability of the result—four separate crew members threw the same prediction—that persuaded the ecowarriors to continue their seemingly hopeless search.

The very next day, Greenpeace filmed a dramatic confrontation with the harpoon ship Vlastny, and the world’s consciousness was transformed.

Emily Hunter laughs when asked, during a call to the Straight from Toronto, if she also consults the I Ching in her work as an environmental activist and filmmaker.

“Yeah, my father taught me early on,” she says, referring to Bob Hunter, the de facto (if reluctant) leader of the group and the principal subject of Change. His appreciation of what Emily calls both “the mechanical and the mystical” is something she feels we could still use.

“For 20 years, in the ’80s and ’90s, there was a hard push towards using sound science as the only way to effectively make change with policymakers or communicate to the media or to our membership,” she continues. “And guess what? The environmental movement really died. The mystics are more than just the spiritual side who are reading the I Ching. It has to do with the creative side, being willing to take risks, being willing to do actions that seem totally implausible but might just work.”

Hunter points to the work of activists in Portland who assailed an Arctic-bound Shell icebreaker from a bridge last week, forcing it (initially) to turn back. As Jerry Rothwell’s documentary illustrates—through archival footage, Hunter’s writings, and the testimony of his earliest partners in the Vancouver-born environmental group—Greenpeace raised global consciousness through a wild formula of inspiration, derring-do, and media savvy. Mounting success also brought exhaustion and chaos, inevitably, from internal divisions.

There’s an almost Shakespearean dimension to the human story here, with Hunter’s former partner Patrick Moore renouncing Greenpeace while infamously taking on consultancy work for nuclear-power and forestry concerns.

That ancient rupture spilled onto the stage when the DOXA Documentary Film Festival presented How to Change the World earlier this year and many of the film’s participants, including Moore, who was booed, took questions after the screening. If Moore is the film’s villain—Bob eventually dubbed him “eco-Judas”—Emily Hunter believes that the depiction is still fair.

“It wasn’t until he started denying climate change and really doing harm on that issue that my father could no longer be friends with him,” she says with a hint of sadness. “I remember he wouldn’t even accept phone calls from him in his dying days. That took a lot for him, and it was painful for my dad. They were really dear friends.”

Emily is every bit as satisfied with the film’s nuanced take on her father.

“Because as much as it reflects his larger vision, it also shows the humanity in him,” she says. “That he wasn’t perfect, that he had his own flaws, and had his own fragility. He’d never want to be portrayed as a hero on a pedestal.”