Good to see that Nik Wallenda successfully crossed Niagara Falls on a high wire yesterday. But defying death requires a confidence that can be self-deluding, as other members of the daredevil family have learned.

Karl Wallenda, founder of the troupe, was 73 when he attempted a relatively simple high-wire stunt in 1978. His mind had become conditioned to success, to being able to live in the sky without a net. He was certain the weakening of his body was no match for his experience and knowledge. A gust of wind was enough to send Wallenda from the wire to his death.

Read also:

• Tales of tightrope walkers (1869-97).