My gender seems to need little encouragement. It comes naturally, like our innate love of maps. In 1260 Marco Polo headed off to find China, and in 1967, when I was seven, I tried to dig a hole straight through from our backyard with my friend Danny Wilson. We gave up at about eight feet, but it made a great fort. Hannibal crosses his famous Alps, and there comes a day in a boy's life when he first crosses the street and enters the company of the great explorers. Scott and Amundsen race for the South Pole, Peary and Cook vie for the North, and when last summer I gave my boys some loose change and permission to ride their bikes down to the store to buy a soda, you'd have thought I'd given them a charter to go find the equator. Magellan sails due west, around the tip of South America—despite warnings that he and his crew will drop off the end of the earth—and Huck Finn heads off down the Mississippi ignoring similar threats. Powell follows the Colorado into the Grand Canyon, even though—no, because—no one has done it before and everyone is saying it can't be done.