The power of an illustration is its relatability with the intended audience. Illustrations about vineyards and wine will not resonate with people who have no understanding of either topic. When a preacher or teacher is adapting illustrations, they must be understood to have any impact.
The following illustration is from Charles Spurgeon and the beauty of this illustration is the timelessness of it. Everyone knows what blisters are like and we all understand that pesky rock or object in the shoe while we walk.
“A stone in your shoe, though almost invisible, will spoil a day’s journey. It is not a great rock to grind you to powder. It is only a little stone, but your foot will blister before you have walked many miles.
How great the pain of a single unconfessed sin! The best thing you can do is to take off your shoe at once and remove the stone before you again put down your foot. So it is with every little sin: If it is only a thought, if it is only a look the wrong way, go to your Father and get rid of it. Do not live a day out of fellowship with God, or an hour under the Lord’s frown.”
Theological Digressions 