Jesus told this parable:

"If a woman has ten silver coins and loses one of them, she will light a lamp, sweep out the house, look in every corner until she has found it. And when she has, she calls her friends and neighbours together, and says, "Rejoice with me! I have found the coin I lost." In the same way, I tell you, there is joy among the angels of God over one sinner who repents." Luke 15:8-10

This is an excerpt from the book, "Faith That Works," by Morris Venden:

In this story Jesus is telling us, through the symbol of the coin, that it is possible to be lost and not to know that we are lost, and not to know the way back. And the One (Jesus) goes out and looks for this lost coin...

It is just a piece of silver, yet it is still of value, and the value of one soul can never be overestimated in the eyes of Heaven."