A marvelous lesson appeared for me just now as I was exiting through the garage.
As I opened the garage door, I startled a large moth, which, upon spreading its wings, displayed a bright red "tail" hidden by the motley brown wings, more a "butterfly" than a moth.
It flew immediately to its perceived escape, the circle-topped window where it frantically tried to exit through the invisible wall of closed glass.
I raised the third-car garage door in hopes of aiding its escape. That caused it to fly higher and become entangled in a spider web. Fearful that it would remain trapped, I selected a long-handled broom to assist it in escaping the tangled threads.
At this, it returned to furiously pumping its wings and banging into the glass, which was, in its perspective, the pathway of escape, but remained its cage.
By simply turning its focus to one side, it would have easily exited its prison. Rather, due to its fixation on one direction, it remained confined, captive.