The story of the Prodigal Son has been long established in Western culture. It’s a message well worn and I won’t pretend I know so much as to somehow come up with a brilliant new interpretation. The lesson takes place within the context of the whole chapter, how God views penitent people as long lost children welcomed home.
First comes the grousing of the Pharisees and scribes that Jesus would mix socially with outcasts from Jewish society. It’s obvious the Pharisees fail to understand the purpose of their covenant. The rituals of Moses were aimed at awakening a sensitivity to our fallen nature. The rituals conferred no merit; there was no such thing in ancient Hebrew thinking. The goal was never ritual purity, but of dealing with the inevitable defilement. The purest heart is the one who goes looking for those who need redemption so they can worship the Lord together.
So we have the parables of the Lost Sheep and the Lost Coin. The former is covered in Matthew, as well. The latter is a similar lesson from a distinctly feminine point of view — a peasant girl whose dowry was so small that any part of it was a treasure in itself. So it is how God views those of His covenant household. If any one of them has gone astray, it’s worth a lot of effort to restore them. Both of those parables represent a common experience among Israeli peasants, that some loss is expected, so life includes established procedures for recovery.
The story of the Prodigal Son drives that point home. We cannot allow ourselves to forget that every part of Israeli existence was tied up in tribal-feudal traditions. A man with two sons would keep an eye on how his property would eventually be divided into three parts: a double portion for the firstborn and a single portion for the other. The younger son has the audacity to press his father for his one-third share from the existing estate. Most fathers would have refused, and rightfully so. However, it was perfectly legal for him to grant this request.
Do you suppose he didn’t know his own son well enough to be surprised how it turned out? The younger son took his fortune and left the covenant lands to live in some exotic place, quite likely Mesopotamia or Egypt. He didn’t want to hear the nagging of his father or his Jewish nation. Fool that he was, the fortune was frittered away, just in time for a famine to strike the land. No longer independent, the boy hired out to some local agrarian. His job was feeding carob pods to pigs. This entailed knocking the pods out of the trees with a stick because the pigs couldn’t reach them, and having the pigs swarm around him to eat. This should have been utterly disgusting work, since Jews considered swine defiling just being near them. As he started thinking about eating those same carob pods, and how much work that entailed, something clicked in his memory.
Even the hired servants on his father’s property back home fared better than he did at this point. So he steeled himself for humility and memorized the speech he would say when he got back home. Eventually he arrived in sight of the place, but as soon as he did, it seemed his father had been waiting for him. The elder man ran to him and didn’t give the younger time to even spill his whole speech. Instead, he embraced the boy and welcomed him home with an extravagant party.
As if that weren’t enough, Jesus rubbed salt in the wound. He described how the elder brother was indignant about this whole scene. The wandering foolish younger sibling, now broke, was living it up. Had his father ever done anything like that for him, after all these years of being faithful to build up the estate? This was clearly the attitude of the Pharisees and scribes. They felt they had been faithful to God, so God owed them. These sinners deserved to be punished for the rest of their lives.
But the father wasn’t having it. Sure, everything he owned now belonged to his elder son, so if had wanted to celebrate God’s mercy, he could have any time he wanted. But no, he was too obsessed with his share of material property, and cared not a whit about his own flesh and blood. The scribes and Pharisees were locked in slavery to the rituals, and boasted of how they piled on extra requirements, but what would they have when the Father settled His estate with the Messiah? The hellish attitude in their hearts would own them, and they would remain outside the final celebration in Heaven. They were already dead in their sins, and only those who repented were alive — such as the penitent publicans and sinners.
I had always thought the father let the son have his inheritance, though it was insulting for the son to ask for it so soon, because as you said, the father knew him well enough to know how it was going to end up. He knew that’s the only way his son was going to learn. Keeping him within the good graces of the family by having him so physically close wouldn’t “cure” him.