Our oldest son Paul is on Yellowstone Lake on a two-week canoe venture. It is his seventh canoe trip on the lake that lies within Yellowstone National Park.

He is alone in a part of the country where there are grizzly bear, moose, elk and deer. At night, while in his tent, he hears wolves howling.

He judges these kinds of trips on the benefit, rather than the difficulty.

And it defines such tri...