“For a brief moment, I feel perfect.” Alex Honnold’s revelatory statement is crucial to understanding the internal drive that led the climber to successfully scale Yosemite’s El Capitan alone, and without equipment—”free solo”—in June 2017. This pursuit is what drives the plot in Free Solo, the 2018 documentary directed by Jimmy Chin and Elizabeth Vasarhelyi.  When applied to Honnold’s staggering feat, “perfection”…