A young girl, a lapsed Catholic, broke her leg . As she was unable to do much, one of her friends asked her if she would like to go to Mass with her and she went along.
The reading was about the Good shepherd going after the lost sheep. And in the sermon the priest was saying that in olden times when a lamb was a bit wayward sometimes the shepherd would break one of its legs, so it would be immobile and unable to run off and would then carry it around on his shoulders while the leg healed.
In that way the lamb would become familiar with the shepherd and less inclined to stray. As the girl was listening to this, its application in her life became clear and she came home to the church and counted the broken leg as a blessing !