Two horses as one

"As you stand and watch these two horses, you’ll see that the horse with the bell is always checking on the blind horse. That the blind horse will listen for the bell and then slowly walk to where the other horse is, trusting that he will not be led astray.

When the horse with the bell returns to the shelter of the barn each evening, it stops occasionally and looks back, making sure that the blind friend isn’t too far behind to hear the bell."

http://www.carolynresnickblog.com/two-horses-as-one.html