Back in high school, I tried out for the school’s marching band.
I wasn’t good at any traditional marching band instrument, such as a trumpet or tuba or slide trombone. I couldn’t even learn how to beat a drum.
“This is going to be impossible,” said the band director. “You’ll need an impossible instrument.”
He pulled open a drawer and lifted a strange twisted triangle that hurt my eyes to look at it.
“Here’s the Penrose,” he said, handing to to me. “Go practice on the stairwell.”
I tapped the triangle and climbed up the stairs… and up… and up…