On a small farm amid gently rolling hills, there was once a playful Labrador retriever named Sartre. Every day Sartre would leap over a fence at the back of the farm to run through the woods and chase squirrels. Eventually, the fence was dismantled, freeing poor Sartre from the burden of having to hop over it every time he wanted to frolic, but Sartre still jumped every time he came to the spot where the barrier had been. He had developed a set of memories and assumptions that made it almost impossible for him to notice the fence was no longer there.
- From Thinking in New Boxes: A New Paradigm for Business Creativity by Luc de Brabandere and Alan Iny