It was on one of his weekend getaways that Irwin found himself sitting in a clearing contemplating suicide. It was difficult to stop thinking about his stepfather. The doctors believed the cancer was the result of his years spent working as a chemical engineer for Union Carbide. Irwin wasn't a doctor, but he knew that when his stepfather came home from work he'd immediately jump in the shower to get the thick layer of chemicals off his skin. And now, when he thought of the cries of pain waiting for him at home, suicide seemed like a good option.

"I heard the trees rustling, and I decided to kill myself. I knew where I was going to go, and what I was going to do."

But something made Irwin pause. "If I'm going to end it, I might as well do something with my life," he told himself. That something became obvious once he looked around him. "I decided that yeah, I liked these trees, and that there were some people who were trying to fuck with them, so that instead of suicide I could try fighting those people. Instead of turning to suicide, I turned to protest."

Irwin's brother Brian recalls seeing a change in Irwin after that. "He was much more reflective, somewhat stormy, he definitely turned inward. I guess he confronted his demons."

Nearly 30 years later, that same conviction is on display in Irwin every Tuesday night when he joins a group of like-minded activists at Barley's Tap Room in the Old Town section of Knoxville, Tennessee. They all believe in some form of radical environmentalism. Most don't have life and death stories of "conversion," but many can point to a moment, a "wilderness experience" as they call it, that convinced them to commit their lives to protecting the environment.

These epiphanies are often reminiscent of spiritual awakenings, according to Dr. Harold Herzog, a psychology professor at Western Carolina University who specializes in moral decision-making and affinity with the outdoors. "The similarities between [activists' moments of] commitment and religious conversion is astounding," Herzog observes. "Then there is the evangelism side, trying to convert others." The form this "evangelism" takes can often be traced back to an activist's own wilderness moment. This can cause friction in radical environmentalist movements -- as members argue for their own personal visions, infighting can ensue and leaders are regularly pushed out.

Irwin knows this all too well. Early in his new life as an environmentalist, he was drawn to an activist group called Earth First! Its co-founder Dave Foreman had experienced his own wilderness moment as a boy -- for Foreman, it arrived in the form of the New Mexico wolf. The first books he'd ever read on his own had been his mother's copies of Wildlife Illustrated and Wildlife of the World. He adored those two hardbound red volumes with their gold lettering and endless renderings of animals. Today he still handles them lovingly, always careful to set them down with both hands on a coffee table. They are still in pristine condition, the covers still attached and the pages bearing few marks. Whenever someone else handles these cherished items, Foreman's eyes stay fixed on the books.