There is an interesting development in the account of the lost and found parables of Luke 15. There are 1 out of 100 sheep, 1 out of 10 coins, and 1 out of two sons. Sinclair Ferguson notes:
Luke 15 contains three parables. In some ways, they are three parts of one larger parable–a single message about lost things being found, each episode told in a context of increased complexity and heightened tension.
Scene one describes a Shepherd who has lost one of his sheep. Sheep were, and are, valuable. But he has lost only one out of one hundred–one percent.
Scene two describes a woman who has lost a silver coin. The coin is valuable to her; perhaps it was saved for a rainy day. She has lost one coin out of ten–ten percent, a much higher percentage loss.
The third scene, however, is much more poignant. The father of two sons looses one of them. He has lost fifty percent of his sons, not a sheep or a coin–an unbearable loss.
Jesus was clearly building up to the main point. The scenes in the third parable are described in much greater legnth, with much greater complexity and depth of emotion. In addition, there are more characters in the third story–two sons and their father–each of whom express his thoughts and feelings about the situation.1
1. Sinclair Ferguson By Grace Alone (Lake Mary, FL: Reformation Trust Publishing, 2010) p. 15