What is strength of mind?

Here’s a little experiment. Take a roll of ordinary duct tape out to your driveway and lay down twenty feet of it in a straight line. Now, remove your shoes and walk that line, making sure to keep at least one foot on the tape at all times.

You’ll find yourself doing an odd kind of shuffle: sliding one foot forward, transferring your weight to it, then balancing on that leg while you advance the other.

With a little practice, if your balance is decent and conditions are favorable, you should be able to traverse the tape without too much trouble.

Ordinary duct tape is 1.88 inches wide. So imagine the tape were even a bit wider — two inches, say, or even two and a half. That’s pretty wide, right? The heels of my pudgy feet are two inches wide; even the widest part of my foot is only about four inches wide. Which means at any given time, most of my foot — and certainly the centerline, including the middle three toes — is planted squarely on the tape.

As I’m sliding along in my socks, hoping the neighbors aren’t watching, I know that if I lose my balance, it’s no big deal. I’ll just go back to the beginning and start over. But the tape is plenty wide; I’m perfectly sober; and staying on the line is simply a matter of concentration.

All of this is to establish that crossing twenty feet of asphalt on a two-inch-wide line of tape is definitely doable, even for a novice tape-walker.

Now. Elevate the line of tape fifteen hundred feet in the air. A muddy river — just a squiggly brown line from his height — winds through a limestone canyon one hundred and fifty stories below you. A misstep will mean certain death — but only after a fall that will last twelve agonizing seconds.

Assume all other conditions were the same — same duct tape; same two-inch-wide ribbon of asphalt underneath; same socks; etc.

Could you still walk that line?

Nik Wallenda could, as he proved last week by traversing a steel cable strung across the Little Colorado River Gorge in Navajo territory in northern Arizona.

Of course, our little thought experiment isn’t exactly fair. Conditions over the Grand Canyon in late June are somewhat different from those that prevail in your driveway. First of all, there’s the deadly desert heat. Then there’s the way the walls of the canyon torture the rising air, making it swirl in great fickle gusts full of blinding grit.

And let’s be completely honest, here. There’s a huge difference between an asphalt driveway and a round steel cable, even if, like Mr. Wallenda, you grew up in a storied circus family, and thus learned to walk on a cable the way that ordinary toddlers stagger across the living room floor.

But the basic principle is sound. Wire-walkers like Mr. Wallenda start their training near the ground, elevating the wire higher and higher as they mature. A few very special performers are capable of transferring what they know to be true near the ground — the wire is wide; my step is sure — to a cable strung at unimaginable heights.

In the world of modern high-wire spectacle, there are plenty of technical challenges to overcome: negotiating for the venue; indemnifying the partners; setting up the wire.

But it all boils down to a man standing on that two-inch cable, willing himself to ignore the seemingly un-ignorable: the river winking facetiously at him at the bottom of the canyon; the knowledge that every minute on the wire could be his last on earth; the tantalizing proximity of friends and family, but only on the other side of a terrifying dance with death.

How does he do it?

In the aftermath of Mr. Wallenda’s breathtaking wire-walk across the Niagara Falls, which I wrote about in these pages on June 28th, 2012, much was made of the religious faith that is the cornerstone of his endeavors. I’ll admit I was a little put off by it, the same way it bugs me a little when athletes gesture to the heavens after a victory.

But anyone watching the coverage of Mr. Wallenda’s recent triumph had front-row seats to an extraordinary testimonial. He wore a headset during the performance, and aside from the occasional calming sound of his father’s voice over the radio, helping him across, the audio consisted of Mr. Wallenda’s praying, a steady hymn of praise and supplication that started a few minutes into the walk, and lasted most of the nearly half an hour that it took him to inch across the gorge.

He prayed to God to calm the wire and to take the tension from his shoulders; he praised Jesus for the glorious vistas and for the splendor of the moment; again and again, as the wind rose and the wire became agitated, he surrendered himself to the will of the Infinite.

I’m not much of a praying man, but no one who watched Mr. Wallenda that day could deny the power of his faith. It sustained him as he defied certain death. It relieved him of the impossible distractions of the moment. It helped him remember how wide the cable was, despite how incredibly thin it must have seemed, set against that awesome backdrop.

In other words, it gave him strength of mind.