Crosby, George’s dog, had been staring at the same spot on the wall for days. He only left this position at mealtime. Even though George had already inspected every bit of wall several times, he decided to get up again and take another look at what was holding his pet’s attention.

And, like all the times before, the dog, Crosby, was convinced George had understood him when he headed for the wall. The happy dog ​​hopped around the room, wagging his tail happily. The inspection had been in vain again, George didn’t understand at all. What was wrong with that wall?