Some medical people believe emotional stress may cause leprosy, and indeed those with the disease felt stress. They felt that if there was a God, that God had forgotten them. Whenever another human came their way, lepers were required to shout: "unclean, unclean." They were segregated from society, and ordered to dress distinctively, so others could avoid them. Within their hell they longed, hoped, and prayed for readmission to society and remission of their dreaded condition. 
Luke says that on that day when Jesus entered their village those ten lepers were "keeping their distance." In reality it was a tremendous gulf, for leprosy was the AIDS of the biblical world.
Somehow they had enough energy and hope to cry out in unison, "Jesus, Master, have mercy on us!" He did and they were "made clean." Yet, the amazing element in the story is not that the ten were healed and released from their horrible state but that only one returned to the source of that healing, to express thanks. Jesus than asks His question that was never answered, "Were not ten made clean? But the other nine, where are they?"
I can answer that question.
The first leper had a flourishing family shipping business at Joppa. He was banished two years before, as a leper-outcast, and his wife and son tried to keep the business going. His competition took advantage of his absence. So, following his cleansing, he headed posthaste for Joppa, as fast as his renewed body would take him.
When the second leper was questioned as to why he did not return, he made this statement, "I didn't want to be healed, because I don't want to live. I find life too difficult. Life is just a rat race, everyone trying to get their piece of manna. I don't want any responsibility. I'd rather die than have to face the difficulties of living. But now — thanks to Jesus — I am forced back onto the old treadmill. Now I've got to find a job, and keep it."
After his encounter with Jesus, the third leper started immediately for Legion, his hometown. He knew his family and friends prayed daily for his cure, and he wanted to show them that prayers are answered, so he never looked back.
The fourth and fifth lepers were close friends. Excitedly they left for Caesarea. After about one hour of travel they realized they had forgotten to thank Jesus. So they retraced their steps, but by the time they returned to the place of their healing, Jesus was gone.
The sixth leper knew he was healed, but he didn't care how it happened. He felt he got lucky, and he just wanted to get away from that seemingly God-forsaken village, so he took his exit.
The seventh leper had three grandchildren whom he had not seen since his banishment four years before. Those years seemed like a lifetime. As soon as he felt the change in his body he headed for those grandchildren at Dotham. He just wanted to be able to hold them.
The eighth leper believed the whole experience was probably just temporary — a momentary remission. How could any one person make a difference in human suffering anyway? Why thank anyone for getting involved? So, after going to the priests, he simply went to the next valley, feeling he would probably be forced to return to the leper colony when the sores reappeared.
A burning love is the reason the ninth leper did not return. Two years, one month and 14 days earlier, on the last night of his freedom from the leper colony, he spent a moonlit evening with a young woman in Jericho. Knowing his condition, she yet had said, "I'll wait for you." Those words had kept him alive. Now he headed for Jericho, on the run. He went with both fear and hope. In fear that she might not be waiting, and in hope that she was.
Why did those nine not return to the source of their healing? The answer is of course as old as Adam and Eve — because they were human. They thought first about their own condition, then about their relationship with other humans, and maybe, finally, about their relationships to the source of their being.
However, their story continues. Two years following the Jesus encounter, lepers four and five accidentally met leper seven in Jerusalem. Overjoyed, they decided to plan an annual reunion-celebration-thanksgiving event at Jerusalem every year. They did, and over the years others who had been in their suffering/healed circle joined them with their families. Before they were forced to be together; now they chose to be together, in the breaking of bread and prayers.
Is this explanation of why the other nine did not return simply an outburst of wild imagination? Maybe. Maybe not. I cannot prove it or disprove it. You have probably given your energy to identifying with the Samaritan who did return. Oh? Is your reaction that quick, your faith that strong? If so, thank God for it.
For all of us the important question is: How do we fit into this story? Can we be thankful for past healing events, and express that thanks, long after the fact?
A friend, Melissa, provides an insight. Melissa grew up in a county seat town in central Indiana. Following her college days, and her venture out into the world, she returned one week to her hometown and was shopping in a grocery store. By chance she met a former high-school classmate. They exchanged greetings, and the usual "Where are you now?" questions and answers, and then they parted.
A few days later Melissa received a letter from this woman that read: "When I bumped into you at the store this week I don't know why I didn't say something, but now I will. Do you remember that weekend when we were seniors and you invited me to attend your church youth retreat? That event changed my life, and I've never told you. During my senior year I was experiencing some deep family problems, and that retreat really saved my life. For some reason I've never thanked you, but now I am. Thank you, Melissa, for caring and for asking me to participate."
Can we be thankful, and express that thanks, after the fact? Yes we can, and yes we should.
What were those healing experiences in your life that made life not only bearable, but enjoyable? Maybe you just failed to see the hand of God entering your life. Indeed those words of Jesus on that day are directed to us, "Get up and go on your way; your faith has made you well."
Only God knows how many times those nine told their story of healing in later years. Maybe what they did, and what we need to do, is to carve out a time where we express to God our thanks for God's loving acceptance of us as-we-are; and a time that results in a yet-stronger faith and more loving service to others.
It is never too late for us to give thanks to the source of our healing and being.