What is the theme in The Wild Muir: Twenty-two of John Muir's Greatest Adventures by John Muir?

Life-threatening activities is a major theme. There is a reason that John Muir is often called "the wild Muir." He routinely engages in hikes and exploratory treks that are clearly life-threatening. For instance, in "An Interview with a Bear," Muir rushes bears just to see how they will run. He seems to be wholly unafraid of the bears and cautions the reader not to be concerned. In "The Snow Avalanche Ride," Muir actually rides an avalanche and survives. While he does not intend to ride the avalanche, he puts himself in a position where that is a viable option. Muir kills several rattlesnakes with just his foot in another shockingly risk action.