There’s an old story, set back in the days when daring tightrope walkers stretched ropes across waterfalls and stepped out over thin air. According to this story, no doubt apocryphal, one such daredevil asked a spectator, “Do you believe I can push this wheelbarrow on that rope across that waterfall?”

The spectator thought for a moment and said, “Yeah, sure.”

“Great,” said the acrobat. “Jump in the wheelbarrow.”