The value of hindsight is extremely important in Jill Paton Walsh's Torch. For instance, it becomes apparent only after one is thoroughly into the book that what the children are toting around the world is the torch that is used to start the Olympic games.
Industrial civilization has long ago been destroyed when two children, Cal and Dio, are sent up the mountain of Olim to get the required blessing of the old village man on the eve of their arranged marriage. They find the old man near death and spend the night trying to make him comfortable. The old man tells Dio that he must stay and "guard the treasure." He dreams that the athletes from Ago will come and claim the treasure. The children do not know what the old man is talking about; they assume he is delirious because he is so near death.
He tells the children that long ago every four years a torch was lit and carried to the games, wherever they were. "If ever they come again, they must be shown where these things are hidden. There has to be a Guardian. You, now." The old man had been Guardian of the torch since he was eighteen years old and he designates Dio as the new Guardian. "They" have never come for the treasure, but the old man still dreams that someone will come. He asks that he not be buried but dropped down the dry well with a cornerstone placed over it.
After the old man has died, a group of Cal's and Dio's friends come to tell them that the grown ups are angry and looking for them. Dio and Cal both realize that things can never be the same because they have spent the evening together before their wedding. Thirteen-year-old Cal has become a "tainted" woman. Dio believes he now has two missions to accomplish: he has to protect Cal as well as keep his promise to guard the treasure the best way he can.
Dio wants to bury the old man before the grown ups come because "it wouldn't be decent," to just leave him there. When the children find the well and struggle to remove the cornerstone they find that it is not an empty well. They find the treasure that consists of a mirrored bowl and a "cone, about three feet long, made of some metal, elaborately etched with a lovely flowing pattern." The children without knowing it had found the last remaining Olympic torch in existence. After the children hide from the elders and get the torch lit from the bowl and the sun, Dio tells them he must go to find a place where the torch is wanted. The children embark on a journey with Dio carrying the lighted torch that will forever change them and everyone they encounter on the way.
They stop in a village to get some warmth and food. The villagers become excited and gather round the children while others run to get "somebody so old and venerable he could not walk or stand, but was brought out in a wooden chair, and set down on the steps of the church. . . . He asked in a steady voice where are the Games."
The children learn more about Olympic games and come to realize that they have in their possession the last remaining torch in existence. The previous guardians had waited at the marble fields for the runner to come for the torch; never had a guardian gone looking for the games. When the children leave the village they are joined by the village's best runner, the Nikathalon and a guide to start their journey to Palcastra where there are reported games. They have many adventures and narrow escapes from death before they meet a scholar who is an authority on the Ago.
He has taught himself to read. He says that it was the ability to read that kept the Ago together for as long as they were together. He believes that "Books are powerful," because they not only teach one how to do some of the simple things from Ago, but they can also teach us why we cannot do the more difficult things like make flying pictures. "If people grasped even that much we would be on the way back . . . as it is, I think we are still on the way down." The children still do not understand, so the scholar explains that it is not so much the knowledge of Ago that is lost, but the way to combine the knowledge of each individual:
In the Ago, then, nobody [could make flying pictures]; that is, no one person. The pictures shone on frames made of glass. It wasn't any use just throwing the pictures into the sky; there had to be frames ready to receive them. Someone knew how to make the frames; or perhaps each person knew only how to make one part of the frames . . . and that is what we have lost. We can do now what anyone can do alone; or what a few people together, as in a family or a village, can do.
Because almost everyone's full understanding of Ago is lost, it is very emotional and meaningful to the scholar that the children have brought the torch to him. It is not only that the torch represents a piece of Ago, it is more that the children carried it through the world without understanding why or what they were doing. The emotion and the impulse of Dio and his friends represent what the scholar knows of the lost past.
The scholar believes that "if we want the wonders of Ago, and if we strive for them we can achieve them again." Dio is skeptical, "How could we achieve what we can barely imagine?" But he starts to understand that it can be achieved by each individual making a small difference such as he and his friends are doing.