Symbolism or Not?

I recently read a small book by Helen Roseveare, Enough.   She talks about her struggles pre-conversion with trying to grasp what the Lord's Supper is all about.  She grew up in the church of England where transubstantiation was taught.  As an adult she heard the Gospel and learned about grace instead of "the way of following rules and regulations." During this time of internal struggle when she is unsure whether she had been taught wrong she states:

I wanted their assurance, their knowledge of God as their Savior, their peace - but I dreaded the possibility of being wrong and forfeiting all the past.  There was an elderly lady at the house party, little Miss Candy. I went to see her to ask her help - how could I be sure? "What is your difficulty?" she asked me.  "In the Bible, when Jesus gave the bread and wine to his disciples at the Last Supper, he said, 'This is my body' and 'This is my blood' - but you people don't believe this!"  Miss Candy asked me to go to the locker by her bedside and bring her the photo that was there.  As I gave it to her she said, "This is my father."  I knew at once what she was saying.  Her father had been dead for many years.  The photo reminded her of her father.  Likewise the bread and wine were to be reminders to us of what Jesus had done for us on the cross."  (pg. 18)

What a simple way to demonstrate the elements of the Lord's Supper are symbols to remind us of what Christ has accomplished for us on the cross.  I like simple object lessons that teach truth.  Not only can they be used with children, but also with adults who are seeking for answers.

Is there an object lesson you have used to teach a biblical principle?