“I never even thought to look for other—oof!” Lunging forward I found myself tripping right over a nice big chunk of nothing. I stumbled forward; my body surged with the heat of concentrated humiliation. Finally I regained my footing and looked awkwardly up at Joel. “Ha,” I said as a failed effort to laugh at myself. With no hesitation Joel turned around and walked over to the spot that I’d tripped. He bent down and took a firm grip on an armful of thin air. He heaved it up into his arms and walked it over to the edge of the sidewalk and tossed it out of the way. He brushed off his hands with vigor and said, “Don’t want anyone else tripping over that invisible log.”