Last Thursday at Hell Roaring Canyon, Potter believed he was finally ready to walk the 180-foot rope while tethered to a leash around his waist. During a couple weeks of rehearsal, he had felt exposed on the rope, with a touch of vertigo. A parabola of sandstone curved off to his right, never more than 60 feet away. To his left, the gorge yawned a half-mile wide. Straight ahead, the rope was anchored to a narrow promontory that seemed to hover, drawing his vision a mile down the canyon.

“When I get in the middle, an emptiness takes over,” Potter said. “I felt a little helpless.”

On his first few attempts at sunset, the temperature dipping into the 30s, Potter straddled the rope as he fell, barrel-rolling into a sitting position and scooting back to the ledge. And then with impeccable balance and concentration, his arms waving in smooth, swooping motions, he reached midway and beyond. The rope was more taut than a regular slackline. Still, it gave about two feet in the middle and moved a foot from side to side. Potter kept his equilibrium. The leash’s metal ring dragged behind him, giving a reassuring scrape along the rope that was amplified by the canyon’s acoustics.

He secured the rope between his two biggest toes, focusing on a yellow flag hanging from the outcropping at the end of the line. He grew more confident and his breathing became shallow and loud and when he covered the distance Potter let out a whoop.

It was at times like this, full of calm and terror, Potter said, that he felt most connected to himself and his surroundings.

“When there’s a death consequence, when you are doing things that if you mess up you die, I like the way it causes my senses to peak,” Potter said. “I can see more clearly. You can think much faster. You hear at a different level. Your foot contact on the line is accentuated. Your sense of balance is heightened. I don’t seem to feel that very often meditating.”

From the time he was a boy, Potter said, he had a recurring dream. He was in the air and people were giving him instructions in high-pitched squeaks, teaching him how to fly. At the end of his dream, he began to fall, dropping toward a dead tree, and then he awakened. As a climber, he came to believe that he might be seeing his own death. But as a highliner and BASE-jumper, he said, he had come to view his dream as an affirmation of flight instead of a portent of mortality.