When she speaks to us from 1968, Adah claims that she needs a religion or something to believe in. Orleanna, she claims, has a religion in the form of her pagan nature-worship and her obsession with forgiveness from Ruth May. Leah too has a religion, Adah claims, in the form of her suffering. Rachel, she admits does not have one and is the happiest of them all, but she argues that Rachel's religion might just be a worship of herself. By the last time she speaks to us from the late nineties, Adah has found a religion. Her religion is science, the facts of the world.
Like Leah's religion, Adah focuses on justice. Adah has given up any lingering belief in a human-centric world, and so thinks of justice in global terms. On a global level, she believes, there can never be any true justice, only balance. The world regulates its population according to its carrying capacity. That is, one life form will always have to die for another to live, whether that is one person for another, one animal, or one virus. She cites Albert Schweitzer's mission to save every African child by providing them with medicine. Though successful in the short term, the overpopulation that resulted has led to deforestation, famine, and drought. Adah does not despair over this ruthless balancing act, but marvels over it. She is able to rise above her human skin and view the world as an objective observer, much as she once viewed her family and Kilanga in this way. From this vantage point the shaky accord between human, plant, virus, and mineral is admirable rather than frustrating. For humans to be winning would mean for the other populations to be losing. It is not even clear what this would mean, other than perhaps for humans to all live to an old age and then die peacefully in their sleep.
Leah, the compassionate person-lover, retains her human-centric focus, and comes to despair of justice even on that more narrow level. Even within human society, she admits, "there is not justice in this world" (Song of the Three Children: Leah Price). In this sphere too there is only the possibility of balance. What balance could mean in this context is not as clear as what it means in the global context, where the symbiosis of different life forms feeding off each other's deaths is well-known. Most likely, in referring to balance in the sphere of human society Leah means only to refer to the easing of inevitable tragedy and injustice that human beings can constantly try to effect.
The book ends with the words, "Walk forward into the light," echoing the familiar motif of lightness and darkness. Until now light has been primarily used to symbolize all that is untainted by an acquisitive greed and arrogance. If we interpret this sentence with that reading in mind, Ruth May seems to be telling her mother to walk away entirely from the world of her husband and the crimes perpetrated in Africa, the world of darkness. That is, she is telling her to forget her associations with that world, and thereby to forget her guilt. Alternatively, here the light might symbolize something much more simple. It might symbolize forgiveness itself. In all likelihood, the light is supposed to symbolize both of these things: the opposite of the dark world of greed and arrogance and also forgiveness. Forgiveness, in fact, might itself be seen as the opposite of the darkness at the heart of the book's dual tragedies.